@article{FortesaGarciaComendadorCalsamigliaetal.2019, author = {Fortesa, Josep and Garc{\´i}a-Comendador, Julian and Calsamiglia, A. and L{\´o}pez-Taraz{\´o}n, Jos{\´e} Andr{\´e}s and Latron, J. and Alorda, B. and Estrany, Joan}, title = {Comparison of stage/discharge rating curves derived from different recording systems}, series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, volume = {665}, journal = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, publisher = {Elsevier Science}, address = {Amsterdam}, issn = {0048-9697}, doi = {10.1016/j.scitotenv.2019.02.158}, pages = {968 -- 981}, year = {2019}, abstract = {Obtaining representative hydrometric values is essential for characterizing extreme events, hydrological dynamics and detecting possible changes on the long-term hydrology. Reliability of streamflow data requires a temporal continuity and a maintenance of the gauging stations, which data are affected by epistemic and random sources of error. An assessment of discharge meterings' and stage-discharge rating curves' uncertainties were carried out by comparing the accuracy of the measuring instruments of two different hydrometric networks (i.e., one analogical and one digital) established in the same river location at the Mediterranean island of Mallorca. Furthermore, the effects of such uncertainties were assessed on the hydrological dynamics, considering the significant global change impacts beset this island. Evaluation was developed at four representative gauging stations of the hydrographic network with analogic (≈40 years) and digital (≈10 years) data series. The study revealed that the largest source of uncertainty in the analogical (28 to 274\%) and in the digital (17-37\%) networks were the stage-discharge rating curves. Their impact on the water resources was also evaluated at the event and annual scales, resulting in an average difference of water yields of 183\% and 142\% respectively. Such improvement on the comprehension of hydrometric networks uncertainties will dramatically benefit the interpretation of the long-term streamflow by providing better insights into the hydrologic and flood hazard planning, management and modelling.}, language = {en} } @misc{JaraSanchezReyesSocquetetal.2018, author = {Jara, Jorge and S{\´a}nchez-Reyes, Hugo and Socquet, Anne and Cotton, Fabrice Pierre and Virieux, Jean and Maksymowicz, Andrei and D{\´i}az-Mojica, John and Walpersdorf, Andrea and Ruiz, Javier and Cotte, Nathalie and Norabuena, Edmundo}, title = {Corrigendum to: Kinematic study of Iquique 2014 Mw 8.1 earthquake: Understanding the segmentation of the seismogenic zone. - (Earth and planetary science letters. - 503 (2018) S. 131 - 143)}, series = {Earth and planetary science letters}, volume = {506}, journal = {Earth and planetary science letters}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2018.11.026}, pages = {347 -- 347}, year = {2018}, abstract = {We study the rupture processes of Iquique earthquake 8.1 (2014/04/01) and its largest aftershock 7.7 (2014/04/03) that ruptured the North Chile subduction zone. High-rate Global Positioning System (GPS) recordings and strong motion data are used to reconstruct the evolution of the slip amplitude, rise time and rupture time of both earthquakes. A two-step inversion scheme is assumed, by first building prior models for both earthquakes from the inversion of the estimated static displacements and then, kinematic inversions in the frequency domain are carried out taken into account this prior information. The preferred model for the mainshock exhibits a seismic moment of 1.73 × 1021 Nm ( 8.1) and maximum slip of ∼9 m, while the aftershock model has a seismic moment of 3.88 × 1020 ( 7.7) and a maximum slip of ∼3 m. For both earthquakes, the final slip distributions show two asperities (a shallow one and a deep one) separated by an area with significant slip deficit. This suggests a segmentation along-dip which might be related to a change of the dipping angle of the subducting slab inferred from gravimetric data. Along-strike, the areas where the seismic ruptures stopped seem to be well correlated with geological features observed from geophysical information (high-resolution bathymetry, gravimetry and coupling maps) that are representative of the long-term segmentation of the subduction margin. Considering the spatially limited portions that were broken by these two earthquakes, our results support the idea that the seismic gap is not filled yet.}, language = {en} } @book{RahmstorfSchellnhuber2020, author = {Rahmstorf, Stefan and Schellnhuber, Hans Joachim}, title = {Der Klimawandel}, series = {Schriftenreihe / Bundeszentrale f{\"u}r politische Bildung ; Band 10520}, journal = {Schriftenreihe / Bundeszentrale f{\"u}r politische Bildung ; Band 10520}, publisher = {Bundeszentrale f{\"u}r politische Bildung}, address = {Bonn}, isbn = {978-3-7425-0520-0}, pages = {144}, year = {2020}, language = {de} } @article{BoessenkoolBuergerHeistermann2017, author = {B{\"o}ssenkool, Berry and B{\"u}rger, Gerd and Heistermann, Maik}, title = {Effects of sample size on estimation of rainfall extremes at high temperatures}, series = {Natural hazards and earth system sciences}, volume = {17}, journal = {Natural hazards and earth system sciences}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-17-1623-2017}, pages = {1623 -- 1629}, year = {2017}, abstract = {High precipitation quantiles tend to rise with temperature, following the so-called Clausius-Clapeyron (CC) scaling. It is often reported that the CC-scaling relation breaks down and even reverts for very high temperatures. In our study, we investigate this reversal using observational climate data from 142 stations across Germany. One of the suggested meteorological explanations for the breakdown is limited moisture supply. Here we argue that, instead, it could simply originate from undersampling. As rainfall frequency generally decreases with higher temperatures, rainfall intensities as dictated by CC scaling are less likely to be recorded than for moderate temperatures. Empirical quantiles are conventionally estimated from order statistics via various forms of plotting position formulas. They have in common that their largest representable return period is given by the sample size. In small samples, high quantiles are underestimated accordingly. The small-sample effect is weaker, or disappears completely, when using parametric quantile estimates from a generalized Pareto distribution (GPD) fitted with L moments. For those, we obtain quantiles of rainfall intensities that continue to rise with temperature.}, language = {en} } @article{DerrasBardCotton2017, author = {Derras, Boumediene and Bard, Pierre-Yves and Cotton, Fabrice Pierre}, title = {V-S30, slope, H-800 and f(0): performance of various site-condition proxies in reducing ground-motion aleatory variability and predicting nonlinear site response}, series = {Earth, planets and space}, volume = {69}, journal = {Earth, planets and space}, publisher = {Springer}, address = {Heidelberg}, issn = {1880-5981}, doi = {10.1186/s40623-017-0718-z}, pages = {1623 -- 1629}, year = {2017}, abstract = {The aim of this paper is to investigate the ability of various site-condition proxies (SCPs) to reduce ground-motion aleatory variability and evaluate how SCPs capture nonlinearity site effects. The SCPs used here are time-averaged shear-wave velocity in the top 30 m (V-S30), the topographical slope (slope), the fundamental resonance frequency (f(0)) and the depth beyond which V-s exceeds 800 m/s (H800). We considered first the performance of each SCP taken alone and then the combined performance of the 6 SCP pairs [V-S30-f(0)], [V-S30-H-800], [f(0)-slope], [H-800-slope], [V-S30-slope] and [f(0)-H-800]. This analysis is performed using a neural network approach including a random effect applied on a KiK-net subset for derivation of ground-motion prediction equations setting the relationship between various ground-motion parameters such as peak ground acceleration, peak ground velocity and pseudo-spectral acceleration PSA (T), and Mw, RJB, focal depth and SCPs. While the choice of SCP is found to have almost no impact on the median groundmotion prediction, it does impact the level of aleatory uncertainty. VS30 is found to perform the best of single proxies at short periods (T < 0.6 s), while f(0) and H-800 perform better at longer periods; considering SCP pairs leads to significant improvements, with particular emphasis on [V-S30-H-800] and [f(0)-slope] pairs. The results also indicate significant nonlinearity on the site terms for soft sites and that the most relevant loading parameter for characterising nonlinear site response is the "stiff" spectral ordinate at the considered period.}, language = {en} } @article{SierLangereisDupontNivetetal.2017, author = {Sier, Mark J. and Langereis, Cor G. and Dupont-Nivet, Guillaume and Feibel, Craig S. and Joordens, Josephine C. A. and van der Lubbe, Jeroen Fiji. and Beck, Catherine C. and Olago, Daniel and Cohen, Andrew}, title = {The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP)}, series = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, volume = {42}, journal = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, publisher = {Elsevier}, address = {Oxford}, organization = {WTK Science Team Members}, issn = {1871-1014}, doi = {10.1016/j.quageo.2017.08.004}, pages = {117 -- 129}, year = {2017}, abstract = {One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing outcrop sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a \&\#8764;216-meter core (WTK13) in 2013 from Early Pleistocene Paleolake Lorenyang deposits in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the WTK13 core, providing a first age model for upcoming HSPDP paleoclimate and paleoenvrionmental studies on the core sediments. Rock magnetic analyses reveal the presence of iron sulfides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai Subchron. From this excellent record, we find no evidence for the 'Vrica Subchron' previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica Subchron have been affected by the oxidation of iron sulfides initially present in the sediments -as evident in the core record- and by subsequent remagnetization. We discuss the implications of the observed geomagnetic record for human evolution studies.}, language = {en} } @misc{KnapmeyerEndrunGolombekOhrnberger2017, author = {Knapmeyer-Endrun, Brigitte and Golombek, Matthew P. and Ohrnberger, Matthias}, title = {Rayleigh Wave Ellipticity Modeling and Inversion for Shallow Structure at the Proposed InSight Landing Site in Elysium Planitia, Mars}, series = {Space science reviews}, volume = {211}, journal = {Space science reviews}, publisher = {Springer}, address = {Dordrecht}, issn = {0038-6308}, doi = {10.1007/s11214-016-0300-1}, pages = {339 -- 382}, year = {2017}, abstract = {The SEIS (Seismic Experiment for Interior Structure) instrument onboard the InSight mission will be the first seismometer directly deployed on the surface of Mars. From studies on the Earth and the Moon, it is well known that site amplification in low-velocity sediments on top of more competent rocks has a strong influence on seismic signals, but can also be used to constrain the subsurface structure. Here we simulate ambient vibration wavefields in a model of the shallow sub-surface at the InSight landing site in Elysium Planitia and demonstrate how the high-frequency Rayleigh wave ellipticity can be extracted from these data and inverted for shallow structure. We find that, depending on model parameters, higher mode ellipticity information can be extracted from single-station data, which significantly reduces uncertainties in inversion. Though the data are most sensitive to properties of the upper-most layer and show a strong trade-off between layer depth and velocity, it is possible to estimate the velocity and thickness of the sub-regolith layer by using reasonable constraints on regolith properties. Model parameters are best constrained if either higher mode data can be used or additional constraints on regolith properties from seismic analysis of the hammer strokes of InSight's heat flow probe HP3 are available. In addition, the Rayleigh wave ellipticity can distinguish between models with a constant regolith velocity and models with a velocity increase in the regolith, information which is difficult to obtain otherwise.}, language = {en} } @article{BaumbachSiegmundMittermeieretal.2017, author = {Baumbach, Lukas and Siegmund, Jonatan F. and Mittermeier, Magdalena and Donner, Reik Volker}, title = {Impacts of temperature extremes on European vegetation during the growing season}, series = {Biogeosciences}, volume = {14}, journal = {Biogeosciences}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1726-4170}, doi = {10.5194/bg-14-4891-2017}, pages = {4891 -- 4903}, year = {2017}, abstract = {Temperature is a key factor controlling plant growth and vitality in the temperate climates of the mid-latitudes like in vast parts of the European continent. Beyond the effect of average conditions, the timings and magnitudes of temperature extremes play a particularly crucial role, which needs to be better understood in the context of projected future rises in the frequency and/or intensity of such events. In this work, we employ event coincidence analysis (ECA) to quantify the likelihood of simultaneous occurrences of extremes in daytime land surface temperature anomalies (LSTAD) and the normalized difference vegetation index (NDVI). We perform this analysis for entire Europe based upon remote sensing data, differentiating between three periods corresponding to different stages of plant development during the growing season. In addition, we analyze the typical elevation and land cover type of the regions showing significantly large event coincidences rates to identify the most severely affected vegetation types. Our results reveal distinct spatio-temporal impact patterns in terms of extraordinarily large co-occurrence rates between several combinations of temperature and NDVI extremes. Croplands are among the most frequently affected land cover types, while elevation is found to have only a minor effect on the spatial distribution of corresponding extreme weather impacts. These findings provide important insights into the vulnerability of European terrestrial ecosystems to extreme temperature events and demonstrate how event-based statistics like ECA can provide a valuable perspective on environmental nexuses.}, language = {en} } @article{AichnerHiltPerillonetal.2017, author = {Aichner, Bernhard and Hilt, Sabine and Perillon, Cecile and Gillefalk, Mikael and Sachse, Dirk}, title = {Biosynthetic hydrogen isotopic fractionation factors during lipid synthesis in submerged aquatic macrophytes: Effect of groundwater discharge and salinity}, series = {Organic geochemistry : the international journal for rapid publication of current research in organic geochemistry and biochemistry}, volume = {113}, journal = {Organic geochemistry : the international journal for rapid publication of current research in organic geochemistry and biochemistry}, publisher = {Elsevier}, address = {Oxford}, issn = {0146-6380}, doi = {10.1016/j.orggeochem.2017.07.021}, pages = {10 -- 16}, year = {2017}, abstract = {Sedimentary lipid biomarkers have become widely used tools for reconstructing past climatic and ecological changes due to their ubiquitous occurrence in lake sediments. In particular, the hydrogen isotopic composition (expressed as delta D values) of leaf wax lipids derived from terrestrial plants has been a focus of research during the last two decades and the understanding of competing environmental and plant physiological factors influencing the delta D values has greatly improved. Comparatively less attention has been paid to lipid biomarkers derived from aquatic plants, although these compounds are abundant in many lacustrine sediments. We therefore conducted a field and laboratory experiment to study the effect of salinity and groundwater discharge on the isotopic composition of aquatic plant biomarkers. We analyzed samples of the common submerged plant species, Potamogeton pectinatus (sago pondweed), which has a wide geographic distribution and can tolerate high salinity. We tested the effect of groundwater discharge (characterized by more negative delta D values relative to lake water) and salinity on the delta D values of n-alkanes from P. pectinatus by comparing plants (i) collected from the oligotrophic freshwater Lake Stechlin (Germany) at shallow littoral depth from locations with and without groundwater discharge, and (ii) plants grown from tubers collected from the eutrophic Lake Muggelsee in nutrient solution at four salinity levels. Isotopically depleted groundwater did not have a significant influence on the delta D values of n-alkanes in Lake Stechlin P. pectinatus and calculated isotopic fractionation factors epsilon(l/w) between lake water and n-alkanes averaged -137 +/- 9\%(n-C-23), -136 +/- 7\%(n-C-25) and -131 +/- 6\%(n-C-27), respectively. Similar epsilon values were calculated for plants from Lake Muggelsee grown in freshwater nutrient solution (-134 +/- 11\% for n-C-23), while greater fractionation was observed at increased salinity values of 10 (163 +/- 12\%) and 15(-172 +/- 15\%). We therefore suggest an average e value of -136 +/- 9\% between source water and the major n-alkanes in P. pectinatus grown under freshwater conditions. Our results demonstrate that isotopic fractionation can increase by 30-40\% at salinity values 10 and 15. These results could be explained either by inhibited plant growth at higher salinity, or by metabolic adaptation to salt stress that remain to be elucidated. A potential salinity effect on dD values of aquatic lipids requires further examination, since this would impact on the interpretation of downcore isotopic data in paleohydrologic studies. (C) 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @article{BoraCottonScherbaumetal.2017, author = {Bora, Sanjay Singh and Cotton, Fabrice Pierre and Scherbaum, Frank and Edwards, Benjamin and Traversa, Paola}, title = {Stochastic source, path and site attenuation parameters and associated variabilities for shallow crustal European earthquakes}, series = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering}, volume = {15}, journal = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering}, publisher = {Springer}, address = {Dordrecht}, issn = {1570-761X}, doi = {10.1007/s10518-017-0167-x}, pages = {4531 -- 4561}, year = {2017}, abstract = {We have analyzed the recently developed pan-European strong motion database, RESORCE-2012: spectral parameters, such as stress drop (stress parameter, Delta sigma), anelastic attenuation (Q), near surface attenuation (kappa(0)) and site amplification have been estimated from observed strong motion recordings. The selected dataset exhibits a bilinear distance-dependent Q model with average kappa(0) value 0.0308 s. Strong regional variations in inelastic attenuation were also observed: frequency-independent Q(0) of 1462 and 601 were estimated for Turkish and Italian data respectively. Due to the strong coupling between Q and kappa(0), the regional variations in Q have strong impact on the estimation of near surface attenuation kappa(0). kappa(0) was estimated as 0.0457 and 0.0261 s for Turkey and Italy respectively. Furthermore, a detailed analysis of the variability in estimated kappa(0) revealed significant within-station variability. The linear site amplification factors were constrained from residual analysis at each station and site-class type. Using the regional Q(0) model and a site-class specific kappa(0), seismic moments (M-0) and source corner frequencies f (c) were estimated from the site corrected empirical Fourier spectra. Delta sigma did not exhibit magnitude dependence. The median Delta sigma value was obtained as 5.75 and 5.65 MPa from inverted and database magnitudes respectively. A comparison of response spectra from the stochastic model (derived herein) with that from (regional) ground motion prediction equations (GMPEs) suggests that the presented seismological parameters can be used to represent the corresponding seismological attributes of the regional GMPEs in a host-to-target adjustment framework. The analysis presented herein can be considered as an update of that undertaken for the previous Euro-Mediterranean strong motion database presented by Edwards and Fah (Geophys J Int 194(2):1190-1202, 2013a).}, language = {en} } @article{BruneCortiRanalli2017, author = {Brune, Sascha and Corti, Giacomo and Ranalli, Giorgio}, title = {Controls of inherited lithospheric heterogeneity on rift linkage: Numerical and analog models of interaction between the Kenyan and Ethiopian rifts across the Turkana depression}, series = {Tectonics}, volume = {36}, journal = {Tectonics}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0278-7407}, doi = {10.1002/2017TC004739}, pages = {1767 -- 1786}, year = {2017}, abstract = {Inherited rheological structures in the lithosphere are expected to have large impact on the architecture of continental rifts. The Turkana depression in the East African Rift connects the Main Ethiopian Rift to the north with the Kenya rift in the south. This region is characterized by a NW-SE trending band of thinned crust inherited from a Mesozoic rifting event, which is cutting the present-day N-S rift trend at high angle. In striking contrast to the narrow rifts in Ethiopia and Kenya, extension in the Turkana region is accommodated in subparallel deformation domains that are laterally distributed over several hundred kilometers. We present both analog experiments and numerical models that reproduce the along-axis transition from narrow rifting in Ethiopia and Kenya to a distributed deformation within the Turkana depression. Similarly to natural observations, our models show that the Ethiopian and Kenyan rifts bend away from each other within the Turkana region, thus forming a right-lateral step over and avoiding a direct link to form a continuous N-S depression. The models reveal five potential types of rift linkage across the preexisting basin: three types where rifts bend away from the inherited structure connecting via a (1) wide or (2) narrow rift or by (3) forming a rotating microplate, (4) a type where rifts bend towards it, and (5) straight rift linkage. The fact that linkage type 1 is realized in the Turkana region provides new insights on the rheological configuration of the Mesozoic rift system at the onset of the recent rift episode. Plain Language Summary The Turkana depression in the Kenya/Ethiopia borderland is most famous for its several million years old human fossils, but it also holds a rich geological history of continental separation. The Turkana region is a lowland located between the East African and Ethiopian domes because its crust and mantle have been stretched in a continent-wide rift event during Cretaceous times about 140-120 Ma ago. This thin lithosphere exerted paramount control on the dynamics of East African rifting in this area, which commenced around 15 Ma ago and persists until today. Combining analog "sandbox" experiments with numerical geodynamic modeling, we find that inherited rift structures explain the dramatic change in rift style from deep, narrow rift basins north and south of the Turkana area to wide, distributed deformation within the Turkana depression. The failed Cretaceous rift is also responsible for the eastward bend of the Ethiopian rift and the westward bend of the Kenyan rift when entering the Turkana depression, which generated the characteristic hook-shaped form of present-day Lake Turkana. Combing two independent modeling techniques-analog and numerical experiments-is a very promising approach allowing to draw robust conclusions about the processes that shape the surface of our planet.}, language = {en} } @article{HeineckeMischkeAdleretal.2017, author = {Heinecke, Liv and Mischke, Steffen and Adler, Karsten and Barth, Anja and Biskaborn, Boris K. and Plessen, Birgit and Nitze, Ingmar and Kuhn, Gerhard and Rajabov, Ilhomjon and Herzschuh, Ulrike}, title = {Climatic and limnological changes at Lake Karakul (Tajikistan) during the last similar to 29 cal ka}, series = {Journal of paleolimnolog}, volume = {58}, journal = {Journal of paleolimnolog}, publisher = {Springer}, address = {Dordrecht}, issn = {0921-2728}, doi = {10.1007/s10933-017-9980-0}, pages = {317 -- 334}, year = {2017}, abstract = {We present results of analyses on a sediment core from Lake Karakul, located in the eastern Pamir Mountains, Tajikistan. The core spans the last similar to 29 cal ka. We investigated and assessed processes internal and external to the lake to infer changes in past moisture availability. Among the variables used to infer lake-external processes, high values of grain-size end-member (EM) 3 (wide grain-size distribution that reflects fluvial input) and high Sr/Rb and Zr/Rb ratios (coinciding with coarse grain sizes), are indicative of moister conditions. High values in EM1, EM2 (peaks of small grain sizes that reflect long-distance dust transport or fine, glacially derived clastic input) and TiO2 (terrigenous input) are thought to reflect greater influence of dry air masses, most likely of Westerly origin. High input of dust from distant sources, beginning before the Last Glacial Maximum (LGM) and continuing to the late glacial, reflects the influence of dry Westerlies, whereas peaks in fluvial input suggest increased moisture availability. The early to early-middle Holocene is characterised by coarse mean grain sizes, indicating constant, high fluvial input and moister conditions in the region. A steady increase in terrigenous dust and a decrease in fluvial input from 6.6 cal ka BP onwards points to the Westerlies as the predominant atmospheric circulation through to present, and marks a return to drier and even arid conditions in the area. Proxies for productivity (TOC, TOC/TN, TOCBr), redox potential (Fe/Mn) and changes in the endogenic carbonate precipitation (TIC, delta(18) OCarb) indicate changes within the lake. Low productivity characterised the lake from the late Pleistocene until 6.6 cal ka BP, and increased rapidly afterwards. Lake level remained low until the LGM, but water depth increased to a maximum during the late glacial and remained high into the early Holocene. Subsequently, the water level decreased to its present stage. Today the lake system is mainly climatically controlled, but the depositional regime is also driven by internal limnogeological processes.}, language = {en} } @article{HeineckeEppReschkeetal.2017, author = {Heinecke, Liv and Epp, Laura Saskia and Reschke, Maria and Stoof-Leichsenring, Kathleen Rosemarie and Mischke, Steffen and Plessen, Birgit and Herzschuh, Ulrike}, title = {Aquatic macrophyte dynamics in Lake Karakul (Eastern Pamir) over the last 29 cal ka revealed by sedimentary ancient DNA and geochemical analyses of macrofossil remains}, series = {Journal of paleolimnolog}, volume = {58}, journal = {Journal of paleolimnolog}, publisher = {Springer}, address = {Dordrecht}, issn = {0921-2728}, doi = {10.1007/s10933-017-9986-7}, pages = {403 -- 417}, year = {2017}, language = {en} } @article{BoersGoswamiGhil2017, author = {Boers, Niklas and Goswami, Bedartha and Ghil, Michael}, title = {A complete representation of uncertainties in layer-counted paleoclimatic archives}, series = {Climate of the past : an interactive open access journal of the European Geosciences Union}, volume = {13}, journal = {Climate of the past : an interactive open access journal of the European Geosciences Union}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1814-9324}, doi = {10.5194/cp-13-1169-2017}, pages = {12}, year = {2017}, abstract = {Accurate time series representation of paleoclimatic proxy records is challenging because such records involve dating errors in addition to proxy measurement errors. Rigorous attention is rarely given to age uncertainties in paleoclimatic research, although the latter can severely bias the results of proxy record analysis. Here, we introduce a Bayesian approach to represent layer-counted proxy records - such as ice cores, sediments, corals, or tree rings - as sequences of probability distributions on absolute, error-free time axes. The method accounts for both proxy measurement errors and uncertainties arising from layer-counting-based dating of the records. An application to oxygen isotope ratios from the North Greenland Ice Core Project (NGRIP) record reveals that the counting errors, although seemingly small, lead to substantial uncertainties in the final representation of the oxygen isotope ratios. In particular, for the older parts of the NGRIP record, our results show that the total uncertainty originating from dating errors has been seriously underestimated. Our method is next applied to deriving the overall uncertainties of the Suigetsu radiocarbon comparison curve, which was recently obtained from varved sediment cores at Lake Suigetsu, Japan. This curve provides the only terrestrial radiocarbon comparison for the time interval 12.5-52.8 kyr BP. The uncertainties derived here can be readily employed to obtain complete error estimates for arbitrary radiometrically dated proxy records of this recent part of the last glacial interval.}, language = {en} } @article{RachEngelsKahmenetal.2017, author = {Rach, Oliver and Engels, S. and Kahmen, A. and Brauer, Achim and Martin-Puertas, C. and van Geel, B. and Sachse, Dirk}, title = {Hydrological and ecological changes in western Europe between 3200 and 2000 years BP derived from lipid biomarker delta D values in lake Meerfelder Maar sediments}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {172}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2017.07.019}, pages = {44 -- 54}, year = {2017}, abstract = {One of the most significant Late Holocene climate shifts occurred around 2800 years ago, when cooler and wetter climate conditions established in western Europe. This shift coincided with an abrupt change in regional atmospheric circulation between 2760 and 2560 cal years BP, which has been linked to a grand solar minimum with the same duration (the Homeric Minimum). We investigated the temporal sequence of hydroclimatic and vegetation changes across this interval of climatic change (Homeric climate oscillation) by using lipid biomarker stable hydrogen isotope ratios (ED values) and pollen assemblages from the annually-laminated sediment record from lake Meerfelder Maar (Germany). Over the investigated interval (3200-2000 varve years BP), terrestrial lipid biomarker ED showed a gradual trend to more negative values, consistent with the western Europe long-term climate trend of the Late Holocene. At ca. 2640 varve years BP we identified a strong increase in aquatic plants and algal remains, indicating a rapid change in the aquatic ecosystem superimposed on this long-term trend. Interestingly, this aquatic ecosystem change was accompanied by large changes in ED values of aquatic lipid biomarkers, such as nC(21) and nC(23) (by between 22 and 30\%(0)). As these variations cannot solely be explained by hydroclimate changes, we suggest that these changes in the Wag value were influenced by changes in n-alkane source organisms. Our results illustrate that if ubiquitous aquatic lipid biomarkers are derived from a limited pool of organisms, changes in lake ecology can be a driving factor for variations on sedimentary lipid MN values, which then could be easily misinterpreted in terms of hydro climatic changes. (C) 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @article{EmbersonGalyHovius2017, author = {Emberson, Robert and Galy, Albert and Hovius, Niels}, title = {Combined effect of carbonate and biotite dissolution in landslides biases silicate weathering proxies}, series = {Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society}, volume = {213}, journal = {Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society}, publisher = {Elsevier}, address = {Oxford}, issn = {0016-7037}, doi = {10.1016/j.gca.2017.07.014}, pages = {418 -- 434}, year = {2017}, abstract = {Long-term estimates of the dissolution of silicate rock are generally derived from a range of isotopic proxies, such as the radiogenic strontium isotope ratio (Sr-87/Sr-86), which are preserved in sediment archives. For these systems to fairly represent silicate weathering, the changes in isotopic ratios in terrestrial surface waters should correspond to changes in the overall silicate dissolution. This assumes that the silicate mineral phases that act as sources of a given isotope dissolve at a rate that is proportional to the overall silicate weathering. Bedrock landsliding exhumes large quantities of fresh rock for weathering in transient storage, and rapid weathering in these deposits is controlled primarily by dissolution of the most reactive phases. In this study, we test the hypothesis that preferential weathering of these labile minerals can decouple the dissolution of strontium sources from the actual silicate weathering rates in the rapidly eroding Western Southern Alps (WSA) of New Zealand. We find that rapid dissolution of relatively radiogenic calcite and biotite in landslides leads to high local fluxes in strontium with isotopic ratios that offer no clear discrimination between sources. These higher fluxes of radiogenic strontium are in contrast to silicate weathering rates in landslides that are not systematically elevated. On a mountain belt scale, radiogenic strontium fluxes are not coupled to volumes of recent landslides in large (>100 km(2)) catchments, but silicate weathering fluxes are. Such decoupling is likely due first to the broad variability in the strontium content of carbonate minerals, and second to the combination of radiogenic strontium released from both biotite and carbonate in recent landslides. This study supports previous work suggesting the limited utility of strontium isotopes as a system to study silicate weathering in the WSA. Crucially however, in settings where bedrock landsliding is a dominant erosive process there is potential for both random and systematic bias in isotope proxies if the most reactive phases exposed for dissolution by landslides disproportionately contribute to the proxy of choice. This clearly suggests that the isotopic composition of marine Sr is a proxy for periods of rapid mountain uplift and erosion rather than for the associated enhanced silicate weathering. (C) 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @article{RubeyBruneHeineetal.2017, author = {Rubey, Michael and Brune, Sascha and Heine, Christian and Davies, D. Rhodri and Williams, Simon E. and M{\"u}ller, R. Dietmar}, title = {role of subducted slabs}, series = {Solid earth}, volume = {8}, journal = {Solid earth}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1869-9510}, doi = {10.5194/se-8-899-2017}, pages = {899 -- 919}, year = {2017}, language = {en} } @article{Buerger2017, author = {B{\"u}rger, Gerhard}, title = {On trend detection}, series = {Hydrological processes}, volume = {31}, journal = {Hydrological processes}, publisher = {Wiley}, address = {Hoboken}, issn = {0885-6087}, doi = {10.1002/hyp.11280}, pages = {4039 -- 4042}, year = {2017}, abstract = {A main obstacle to trend detection in time series occurs when they are autocorrelated. By reducing the effective sample size of a series, autocorrelation leads to decreased trend significance. Numerous recipes attempt to mitigate the effect of autocorrelation, either by adjusting for the reduced effective sample size or by removing the autocorrelated components of a series. This short note deals with the latter, also called prewhitening (PW). It is known that removal of autocorrelation also removes part of the trend, which may affect the signal-to-noise ratio. Two popular methods have dealt with this problem, the trend-free prewhitening (TFPW) and the iterative prewhitening. Although it is generally accepted that both methods reduce the adverse effects of PW on the trend magnitude, corresponding effects on statistical significance have not been clearly stated for TFPW. Using a Monte Carlo approach, it is demonstrated that both methods entail quite different Type-I error rates. The iterative prewhitening produces rates that are generally close to the nominal significance level. The TFPW, however, shows very high Type-I error rates with increasing autocorrelation. The corresponding rate of false trend detections is unacceptable for applications, so that published trends based on TFPW need to be reassessed.}, language = {en} } @article{NegiPaulCescaetal.2017, author = {Negi, Sanjay S. and Paul, Ajay and Cesca, Simone and Kamal, and Kriegerowski, Marius and Mahesh, P. and Gupta, Sandeep}, title = {Crustal velocity structure and earthquake processes of Garhwal-Kumaun Himalaya: Constraints from regional waveform inversion and array beam modeling}, series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, volume = {712}, journal = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0040-1951}, doi = {10.1016/j.tecto.2017.05.007}, pages = {45 -- 63}, year = {2017}, abstract = {In order to understand present day earthquake kinematics at the Indian plate boundary, we analyse seismic broadband data recorded between 2007 and 2015 by the regional network in the Garhwal-Kumaun region, northwest Himalaya. We first estimate a local 1-D velocity model for the computation of reliable Green's functions, based on 2837 P-wave and 2680 S-wave arrivals from 251 well located earthquakes. The resulting 1-D crustal structure yields a 4-layer velocity model down to the depths of 20 km. A fifth homogeneous layer extends down to 46 km, constraining the Moho using travel-time distance curve method. We then employ a multistep moment tensor (MT) inversion algorithm to infer seismic moment tensors of 11 moderate earthquakes with Mw magnitude in the range 4.0-5.0. The method provides a fast MT inversion for future monitoring of local seismicity, since Green's functions database has been prepared. To further support the moment tensor solutions, we additionally model P phase beams at seismic arrays at teleseismic distances. The MT inversion result reveals the presence of dominant thrust fault kinematics persisting along the Himalayan belt. Shallow low and high angle thrust faulting is the dominating mechanism in the Garhwal-Kumaun Himalaya. The centroid depths for these moderate earthquakes are shallow between 1 and 12 km. The beam modeling result confirm hypocentral depth estimates between 1 and 7 km. The updated seismicity, constrained source mechanism and depth results indicate typical setting of duplexes above the mid crustal ramp where slip is confirmed along out-of-sequence thrusting. The involvement of Tons thrust sheet in out-of-sequence thrusting indicate Tons thrust to be the principal active thrust at shallow depth in the Himalayan region. Our results thus support the critical taper wedge theory, where we infer the microseismicity cluster as a result of intense activity within the Lesser Himalayan Duplex (LHD) system.}, language = {en} } @article{MarkovicCarrizoKaercheretal.2017, author = {Markovic, Danijela and Carrizo, Savrina F. and Kaercher, Oskar and Walz, Ariane and David, Jonathan N. W.}, title = {Vulnerability of European freshwater catchments to climate change}, series = {Global change biology}, volume = {23}, journal = {Global change biology}, publisher = {Wiley}, address = {Hoboken}, issn = {1354-1013}, doi = {10.1111/gcb.13657}, pages = {3567 -- 3580}, year = {2017}, abstract = {Climate change is expected to exacerbate the current threats to freshwater ecosystems, yet multifaceted studies on the potential impacts of climate change on freshwater biodiversity at scales that inform management planning are lacking. The aim of this study was to fill this void through the development of a novel framework for assessing climate change vulnerability tailored to freshwater ecosystems. The three dimensions of climate change vulnerability are as follows: (i) exposure to climate change, (ii) sensitivity to altered environmental conditions and (iii) resilience potential. Our vulnerability framework includes 1685 freshwater species of plants, fishes, molluscs, odonates, amphibians, crayfish and turtles alongside key features within and between catchments, such as topography and connectivity. Several methodologies were used to combine these dimensions across a variety of future climate change models and scenarios. The resulting indices were overlaid to assess the vulnerability of European freshwater ecosystems at the catchment scale (18 783 catchments). The Balkan Lakes Ohrid and Prespa and Mediterranean islands emerge as most vulnerable to climate change. For the 2030s, we showed a consensus among the applied methods whereby up to 573 lake and river catchments are highly vulnerable to climate change. The anthropogenic disruption of hydrological habitat connectivity by dams is the major factor reducing climate change resilience. A gap analysis demonstrated that the current European protected area network covers <25\% of the most vulnerable catchments. Practical steps need to be taken to ensure the persistence of freshwater biodiversity under climate change. Priority should be placed on enhancing stakeholder cooperation at the major basin scale towards preventing further degradation of freshwater ecosystems and maintaining connectivity among catchments. The catchments identified as most vulnerable to climate change provide preliminary targets for development of climate change conservation management and mitigation strategies.}, language = {en} } @article{MischkeLaiAichneretal.2017, author = {Mischke, Steffen and Lai, Zhongping and Aichner, Bernhard and Heinecke, Liv and Mahmoudov, Zafar and Kuessner, Marie and Herzschuh, Ulrike}, title = {Radiocarbon and optically stimulated luminescence dating of sediments from Lake Karakul, Tajikistan}, series = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, volume = {41}, journal = {Quaternary geochronology : the international research and review journal on advances in quaternary dating techniques}, publisher = {Elsevier}, address = {Oxford}, issn = {1871-1014}, doi = {10.1016/j.quageo.2017.05.008}, pages = {51 -- 61}, year = {2017}, abstract = {Lake Karakul in the eastern Pamirs is a large and closed-basin lake in a partly glaciated catchment. Two parallel sediment cores were collected from 12 m water depth. The cores were correlated using XRF analysis and dated using radiocarbon and OSL techniques. The age results of the two dating methods are generally in agreement. The correlated composite core of 12.26 m length represents continuous accumulation of sediments in the lake basin since 31 ka. The lake reservoir effect (LRE) remained relatively constant over this period. High sediment accumulation rates (SedARs) were recorded before 23 ka and after 6.5 ka. The relatively close position of the coring location near the eastern shore of the lake implies that high SedARs resulted from low lake levels. Thus, high SedARs and lower lake levels before 23 ka probably reflect cold and dry climate conditions that inhibited the arrival of moist air at high elevation in the eastern Pamirs. Low lake levels after 6.5 ka were probably caused by declining temperatures after the warmer early Holocene, which had caused a reduction in water resources stored as snow, ice and frozen ground in the catchment. Low SedARs during 23-6.5 ka suggest increased lake levels in Lake Karakul. A short-lived increase of SedARs at 15 ka probably corresponds to the rapid melting of glaciers in the Karakul catchment during the Greenland Interstadial le, shortly after glaciers in the catchment had reached their maximum extents. The sediment cores from Lake Karakul represent an important climate archive with robust chronology for the last glacial interglacial cycle from Central Asia. (C) 2017 Elsevier B.V. All rights reserved.}, language = {en} } @article{EgholmJansenBraedstrupetal.2017, author = {Egholm, David L. and Jansen, John D. and Braedstrup, Christian F. and Pedersen, Vivi K. and Andersen, Jane Lund and Ugelvig, Sofie V. and Larsen, Nicolaj K. and Knudsen, Mads F.}, title = {Formation of plateau landscapes on glaciated continental margins}, series = {Nature geoscience}, volume = {10}, journal = {Nature geoscience}, publisher = {Nature Publ. Group}, address = {New York}, issn = {1752-0894}, doi = {10.1038/NGEO2980}, pages = {592 -- +}, year = {2017}, abstract = {Low-relief plateaus separated by deeply incised fjords are hallmarks of glaciated, passive continental margins. Spectacular examples fringe the once ice-covered North Atlantic coasts of Greenland, Norway and Canada, but low-relief plateau landscapes also underlie present-day ice sheets in Antarctica and Greenland. Dissected plateaus have long been viewed as the outcome of selective linear erosion by ice sheets that focus incision in glacial troughs, leaving the intervening landscapes essentially unaffected. According to this hypothesis, the plateaus are remnants of preglacial low-relief topography. However, here we use computational experiments to show that, like fjords, plateaus are emergent properties of long-term ice-sheet erosion. Ice sheets can either increase or decrease subglacial relief depending on the wavelength of the underlying topography, and plateau topography arises dynamically from evolving feedbacks between topography, ice dynamics and erosion over million-year timescales. This new mechanistic explanation for plateau formation opens the possibility of plateaus contributing significantly to accelerated sediment flux at the onset of the late Cenozoic glaciations, before becoming stable later in the Quaternary.}, language = {en} } @article{NeillJankowskiBrandoetal.2017, author = {Neill, Christopher and Jankowski, KathiJo and Brando, Paulo M. and Coe, Michael T. and Deegan, Linda A. and Macedo, Marcia N. and Riskin, Shelby H. and Porder, Stephen and Elsenbeer, Helmut and Krusche, Alex V.}, title = {Surprisingly Modest Water Quality Impacts From Expansion and Intensification of Large-Sscale Commercial Agriculture in the Brazilian Amazon-Cerrado Region}, series = {Tropical conservation science}, volume = {10}, journal = {Tropical conservation science}, publisher = {Sage Publ.}, address = {Thousand Oaks}, issn = {1940-0829}, doi = {10.1177/1940082917720669}, pages = {5}, year = {2017}, abstract = {Large-scale commercial cropping of soybeans expanded in the tropical Amazon and Cerrado biomes of Brazil after 1990. More recently, cropping intensified from single-cropping of soybeans to double-cropping of soybeans with corn or cotton. Cropland expansion and intensification, and the accompanying use of mineral fertilizers, raise concerns about whether nutrient runoff and impacts to surface waters will be similar to those experienced in commercial cropland regions at temperate latitudes. We quantified water infiltration through soils, water yield, and streamwater chemistry in watersheds draining native tropical forest and single-and double-cropped areas on the level, deep, highly weathered soils where cropland expansion and intensification typically occurs. Although water yield increased four-fold from croplands, streamwater chemistry remained largely unchanged. Soil characteristics exerted important control over the movement of nitrogen (N) and phosphorus (P) into streams. High soil infiltration rates prevented surface erosion and movement of particulate P, while P fixation in surface soils restricted P movement to deeper soil layers. Nitrogen retention in deep soils, likely by anion exchange, also appeared to limit N leaching and export in streamwater from both single-and double-cropped watersheds that received nitrogen fertilizer. These mechanisms led to lower streamwater P and N concentrations and lower watershed N and P export than would be expected, based on studies from temperate croplands with similar cropping and fertilizer application practices.}, language = {en} } @article{StinnesbeckBeckerHeringetal.2017, author = {Stinnesbeck, Wolfgang and Becker, Julia and Hering, Fabio and Frey, Eberhard and Gonzalez Gonzalez, Arturo and Fohlmeister, Jens Bernd and Stinnesbeck, Sarah and Frank, Norbert and Terrazas Mata, Alejandro and Elena Benavente, Martha and Aviles Olguin, Jeronimo and Aceves Nunez, Eugenio and Zell, Patrick and Deininger, Michael}, title = {The earliest settlers of Mesoamerica date back to the late Pleistocene}, series = {PLoS one}, volume = {12}, journal = {PLoS one}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0183345}, pages = {20}, year = {2017}, abstract = {Preceramic human skeletal remains preserved in submerged caves near Tulum in the Mexican state of Quintana Roo, Mexico, reveal conflicting results regarding C-14 dating. Here we use U-series techniques for dating a stalagmite overgrowing the pelvis of a human skeleton discovered in the submerged Chan Hol cave. The oldest closed system U/Th age comes from around 21 mm above the pelvis defining the terminus ante quem for the pelvis to 11311 +/- 370 y BP. However, the skeleton might be considerable older, probably as old as 13 ky BP as indicated by the speleothem stable isotope data. The Chan Hol individual confirms a late Pleistocene settling of Mesoamerica and represents one of the oldest human osteological remains in America.}, language = {en} } @article{KornhuberPetoukhovKarolyetal.2017, author = {Kornhuber, Kai and Petoukhov, Vladimir and Karoly, D. and Petri, Stefan and Rahmstorf, Stefan and Coumou, Dim}, title = {Summertime Planetary Wave Resonance in the Northern and Southern Hemispheres}, series = {Journal of climate}, volume = {30}, journal = {Journal of climate}, publisher = {American Meteorological Soc.}, address = {Boston}, issn = {0894-8755}, doi = {10.1175/JCLI-D-16-0703.1}, pages = {6133 -- 6150}, year = {2017}, language = {en} } @article{WangBekeschusHandorfetal.2017, author = {Wang, Yongbo and Bekeschus, Benjamin and Handorf, Doerthe and Liu, Xingqi and Dallmeyer, Anne and Herzschuh, Ulrike}, title = {Coherent tropical-subtropical Holocene see-saw moisture patterns in the Eastern Hemisphere monsoon systems}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {169}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2017.06.006}, pages = {231 -- 242}, year = {2017}, abstract = {The concept of a Global Monsoon (GM) has been proposed based on modern precipitation observations, but its application over a wide range of temporal scales is still under debate. Here, we present a synthesis of 268 continental paleo-moisture records collected from monsoonal systems in the Eastern Hemisphere, including the East Asian Monsoon (EAsM), the Indian Monsoon (IM), the East African Monsoon (EAfM), and the Australian Monsoon (AuM) covering the last 18,000 years. The overall pattern of late Glacial to Holocene moisture change is consistent with those inferred from ice cores and marine records. With respect to the last 10,000 years (10 ka), i.e. a period that has high spatial coverage, a Fuzzy c-Means clustering analysis of the moisture index records together with "Xie-Beni" index reveals four clusters of our data set. The paleoclimatic meaning of each cluster is interpreted considering the temporal evolution and spatial distribution patterns. The major trend in the tropical AuM, EAfM, and IM regions is a gradual decrease in moisture conditions since the early Holocene. Moisture changes in the EAsM regions show maximum index values between 8 and 6 ka. However, records located in nearby subtropical areas, i.e. in regions not influenced by the intertropical convergence zone, show an opposite trend compared to the tropical monsoon regions (AuM, EAfM and IM), i.e. a gradual increase. Analyses of modern meteorological data reveal the same spatial patterns as in the paleoclimate records such that, in times of overall monsoon strengthening, lower precipitation rates are observed in the nearby subtropical areas. We explain this pattern as the effect of a strong monsoon circulation suppressing air uplift in nearby subtropical areas, and hence hindering precipitation. By analogy to the modern system, this would mean that during the early Holocene strong monsoon period, the intensified ascending airflows within the monsoon domains led to relatively weaker ascending or even descending airflows in the adjacent subtropical regions, resulting in a precipitation deficit compared to the late Holocene. Our conceptual model therefore integrates regionally contrasting moisture changes into the Global Monsoon hypothesis. (C) 2017 Elsevier Ltd. All rights reserved.}, language = {en} } @article{SchmidtWalzMartinLopezetal.2017, author = {Schmidt, Katja and Walz, Ariane and Martin-Lopez, Berta and Sachse, Rene}, title = {Testing socio-cultural valuation methods of ecosystem services to explain land use preferences}, series = {Ecosystem Services : Science, Policy and Practice}, volume = {26}, journal = {Ecosystem Services : Science, Policy and Practice}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2212-0416}, doi = {10.1016/j.ecoser.2017.07.001}, pages = {270 -- 288}, year = {2017}, abstract = {Socio-cultural valuation still emerges as a methodological field in ecosystem service (ES) research and until now lacks consistent formalisation and balanced application in ES assessments. In this study, we examine the explanatory value of ES values for land use preferences. We use 563 responses to a survey about the Pentland Hills regional park in Scotland. Specifically, we aim to (1) identify clusters of land use preferences by using a novel visualisation tool, (2) test if socio-cultural values of ESs or (3) user characteristics are linked with land use preferences, and (4) determine whether both socio-cultural values of ESs and user characteristics can predict land use preferences. Our results suggest that there are five groups of people with different land use preferences, ranging from forest and nature enthusiasts to traditionalists, multi-functionalists and recreation seekers. Rating and weighting of ESs and user characteristics were associated with different clusters. Neither socio-cultural values nor user characteristics were suitable predictors for land use preferences. While several studies have explored land use preferences by identifying socio-cultural values in the past, our findings imply that in this case study ES values inform about general perceptions but do not replace the assessment of land use preferences. (C) 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license.}, language = {en} } @article{HuaCookFohlmeisteretal.2017, author = {Hua, Quan and Cook, Duncan and Fohlmeister, Jens Bernd and Penny, Dan and Bishop, Paul and Buckman, Solomon}, title = {Radiocarbon Dating of a Speleothem Record of Paleoclimate for Angkor, Cambodia}, series = {Radiocarbon : an international journal of cosmogenic isotope research}, volume = {59}, journal = {Radiocarbon : an international journal of cosmogenic isotope research}, number = {Special Issue 6 / 2}, publisher = {The University of Arizona, Department of Geosciences}, address = {Tucson, Ariz.}, issn = {0033-8222}, doi = {10.1017/RDC.2017.115}, pages = {1873 -- 1890}, year = {2017}, abstract = {We report the chronological construction for the top portion of a speleothem, PC1, from southern Cambodia with the aim of reconstructing a continuous high-resolution climate record covering the fluorescence and decline of the medieval Khmer kingdom and its capital at Angkor (similar to 9th-15th centuries AD). Earlier attempts to date PC1 by the standard U-Th method proved unsuccessful. We have therefore dated this speleothem using radiocarbon. Fifty carbonate samples along the growth axis of PC1 were collected for accelerator mass spectrometry (AMS) analysis. Chronological reconstruction for PC1 was achieved using two different approaches described by Hua et al. (2012a) and Lechleitner et al. (2016a). Excellent concordance between the two age-depth models indicates that the top similar to 47 mm of PC1 grew during the last millennium with a growth hiatus during similar to 1250-1650 AD, resulting from a large change in measured C-14 values at 34.4-35.2 mm depth. The timing of the growth hiatus covers the period of decades-long droughts during the 14th-16th centuries AD indicated in regional climate records.}, language = {en} } @article{BernardezPregoVirginiaFilgueirasetal.2017, author = {Bernardez, Patricia and Prego, Ricardo and Virginia Filgueiras, Ana and Ospina-Alvarez, Natalia and Santos-Echeandia, Juan and Angel Alvarez-Vazquez, Miguel and Caetano, Miguel}, title = {Lithogenic sources, composition and intra-annual variability of suspended particulate matter supplied from rivers to the Northern Galician Rias (Bay of Biscay)}, series = {Journal of sea research}, volume = {130}, journal = {Journal of sea research}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1385-1101}, doi = {10.1016/j.seares.2017.05.006}, pages = {73 -- 84}, year = {2017}, abstract = {Scarce research about small European rivers from non-human impacted areas to determine their natural background state has been undertaken. During the annual hydrological cycle of 2008-9 the patterns of particulate supply (SPM, POC, PON, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, V, Zn) from the rivers Sor, Mera Landro, Lourido and Landoi to the Northern Galician Rias (SW Bay of Biscay) were tackled. No differences in the composition of the SPM were detected for the studied rivers regarding Al, Fe and POC but the relative percentage of particulate trace elements (PTE) discriminate the rivers. So, Cr, Co and Ni in the Lourido, and Landoi rivers, and Cu in the Mera River, are controlled by watershed minerals of Ortegal Geological Complex while for the rest rivers PTE are by granitic and Ollo de Sapo bedrock watershed. Therefore, the imprint of PTE in the parental rocks of the river basins is reflected on the coastal sediments of the Rias. The main process controlling the dynamics and variations of chemical elements in the particulate form is the river discharge. This fact exemplifies that these rivers presents a natural behavior not being highly influenced by anthropogenic activities.}, language = {en} } @article{WeisshuhnRecklingStachowetal.2017, author = {Weisshuhn, Peter and Reckling, Moritz and Stachow, Ulrich and Wiggering, Hubert}, title = {Supporting Agricultural Ecosystem Services through the Integration of Perennial Polycultures into Crop Rotations}, series = {Sustainability}, volume = {9}, journal = {Sustainability}, publisher = {MDPI}, address = {Basel}, issn = {2071-1050}, doi = {10.3390/su9122267}, pages = {20}, year = {2017}, abstract = {This review analyzes the potential role and long-term effects of field perennial polycultures (mixtures) in agricultural systems, with the aim of reducing the trade-offs between provisioning and regulating ecosystem services. First, crop rotations are identified as a suitable tool for the assessment of the long-term effects of perennial polycultures on ecosystem services, which are not visible at the single-crop level. Second, the ability of perennial polycultures to support ecosystem services when used in crop rotations is quantified through eight agricultural ecosystem services. Legume-grass mixtures and wildflower mixtures are used as examples of perennial polycultures, and compared with silage maize as a typical crop for biomass production. Perennial polycultures enhance soil fertility, soil protection, climate regulation, pollination, pest and weed control, and landscape aesthetics compared with maize. They also score lower for biomass production compared with maize, which confirms the trade-off between provisioning and regulating ecosystem services. However, the additional positive factors provided by perennial polycultures, such as reduced costs for mineral fertilizer, pesticides, and soil tillage, and a significant preceding crop effect that increases the yields of subsequent crops, should be taken into account. However, a full assessment of agricultural ecosystem services requires a more holistic analysis that is beyond the capabilities of current frameworks.}, language = {en} } @article{KrolJaegerBronstertetal.2006, author = {Krol, Maarten and Jaeger, Annekathrin and Bronstert, Axel and G{\"u}ntner, Andreas}, title = {Integrated modelling of climate, water, soil, agricultural and socio-economic processes: A general introduction of the methodology and some exemplary results from the semi-arid north-east of Brazil}, series = {Journal of hydrology}, volume = {328}, journal = {Journal of hydrology}, number = {3-4}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2005.12.021}, pages = {417 -- 431}, year = {2006}, abstract = {Many semi-arid regions are characterised by water scarcity and vulnerability of natural resources, pronounced climatic variability and social stress. Integrated studies including climatotogy, hydrology, and socio-econornic studies are required both for analysing the dynamic natural conditions and to assess possible strategies to make semi-arid regions Less vulnerable to the present and changing climate. The model introduced here dynamically describes the retationships between climate forcing, water availability, agriculture and selected societal processes. The model has been tailored to simulate the rather complex situation in the semi-and north-eastern Brazil in a quantitative manner including the sensitivity to external forcing, such as climate change. The selected results presented show the general functioning of the integrated model, with a primary focus on climate change impacts. It becomes evident that due to Large differences in regional climate scenarios, it is still impossible to give quantitative values for the most probable development, e.g., to assign probabilities to the simulated results. However, it becomes clear that water is a very crucial factor, and that an efficient and ecologically sound water management is a key question for the further development of that semi-arid region. The simulation results show that, independent of the differences in climate change scenarios, rain-fed farming is more vulnerable to drought impacts compared to irrigated farming. However, the capacity of irrigation and other water infrastructure systems to enhance resilience in respect to climatic fluctuations is significantly constrained given a significant negative precipitation trend. (c) 2005 Elsevier B.V. All rights reserved.}, language = {en} } @article{ParkLuehrKervalishvilietal.2015, author = {Park, Jaeheung and L{\"u}hr, Hermann and Kervalishvili, Guram N. and Rauberg, Jan and Michaelis, Ingo and Stolle, Claudia and Kwak, Young-Sil}, title = {Nighttime magnetic field fluctuations in the topside ionosphere at midlatitudes and their relation to medium-scale traveling ionospheric disturbances: The spatial structure and scale sizes}, series = {Journal of geophysical research : Space physics}, volume = {120}, journal = {Journal of geophysical research : Space physics}, number = {8}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9380}, doi = {10.1002/2015JA021315}, pages = {6818 -- 6830}, year = {2015}, abstract = {Previous studies suggested that electric and/or magnetic field fluctuations observed in the nighttime topside ionosphere at midlatitudes generally originate from quiet time nocturnal medium-scale traveling ionospheric disturbances (MSTIDs). However, decisive evidences for the connection between the two have been missing. In this study we make use of the multispacecraft observations of midlatitude magnetic fluctuations (MMFs) in the nighttime topside ionosphere by the Swarm constellation. The analysis results show that the area hosting MMFs is elongated in the NW-SE (NE-SW) direction in the Northern (Southern) Hemisphere. The elongation direction and the magnetic field polarization support that the area hosting MMFs is nearly field aligned. All these properties of MMFs suggest that they have close relationship with MSTIDs. Expectation values of root-mean-square field-aligned currents associated with MMFs are up to about 4nA/m(2). MMF coherency significantly drops for longitudinal distances of 1 degrees.}, language = {en} } @article{BraunGemignanivanderBeek2018, author = {Braun, Jean and Gemignani, Lorenzo and van der Beek, Peter}, title = {Extracting information on the spatial variability in erosion rate stored in detrital cooling age distributions in river sands}, series = {Earth surface dynamics}, volume = {6}, journal = {Earth surface dynamics}, number = {1}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {2196-6311}, doi = {10.5194/esurf-6-257-2018}, pages = {257 -- 270}, year = {2018}, abstract = {One of the main purposes of detrital thermochronology is to provide constraints on the regional-scale exhumation rate and its spatial variability in actively eroding mountain ranges. Procedures that use cooling age distributions coupled with hypsometry and thermal models have been developed in order to extract quantitative estimates of erosion rate and its spatial distribution, assuming steady state between tectonic uplift and erosion. This hypothesis precludes the use of these procedures to assess the likely transient response of mountain belts to changes in tectonic or climatic forcing. Other methods are based on an a priori knowledge of the in situ distribution of ages to interpret the detrital age distributions. In this paper, we describe a simple method that, using the observed detrital mineral age distributions collected along a river, allows us to extract information about the relative distribution of erosion rates in an eroding catchment without relying on a steady-state assumption, the value of thermal parameters or an a priori knowledge of in situ age distributions. The model is based on a relatively low number of parameters describing lithological variability among the various sub-catchments and their sizes and only uses the raw ages. The method we propose is tested against synthetic age distributions to demonstrate its accuracy and the optimum conditions for it use. In order to illustrate the method, we invert age distributions collected along the main trunk of the Tsangpo-Siang-Brahmaputra river system in the eastern Himalaya. From the inversion of the cooling age distributions we predict present-day erosion rates of the catchments along the Tsangpo-Siang-Brahmaputra river system, as well as some of its tributaries. We show that detrital age distributions contain dual information about present-day erosion rate, i. e., from the predicted distribution of surface ages within each catchment and from the relative contribution of any given catchment to the river distribution. The method additionally allows comparing modern erosion rates to long-term exhumation rates. We provide a simple implementation of the method in Python code within a Jupyter Notebook that includes the data used in this paper for illustration purposes.}, language = {en} } @article{HemingwayHiltonHoviusetal.2018, author = {Hemingway, Jordon Dennis and Hilton, Robert G. and Hovius, Niels and Eglinton, Timothy I. and Haghipour, Negar and Wacker, Lukas and Chen, Meng-Chiang and Galy, Valier V.}, title = {Microbial oxidation of lithospheric organic carbon in rapidly eroding tropical mountain soils}, series = {Science}, volume = {360}, journal = {Science}, number = {6385}, publisher = {American Assoc. for the Advancement of Science}, address = {Washington}, issn = {0036-8075}, doi = {10.1126/science.aao6463}, pages = {209 -- +}, year = {2018}, abstract = {Lithospheric organic carbon ("petrogenic"; OCpetro) is oxidized during exhumation and subsequent erosion of mountain ranges. This process is a considerable source of carbon dioxide (CO2) to the atmosphere over geologic time scales, but the mechanisms that govern oxidation rates in mountain landscapes are poorly constrained. We demonstrate that, on average, 67 +/- 11\% of the OCpetro initially present in bedrock exhumed from the tropical, rapidly eroding Central Range of Taiwan is oxidized in soils, leading to CO2 emissions of 6.1 to 18.6 metric tons of carbon per square kilometer per year. The molecular and isotopic evolution of bulk OC and lipid biomarkers during soil formation reveals that OCpetro remineralization is microbially mediated. Rapid oxidation in mountain soils drives CO2 emission fluxes that increase with erosion rate, thereby counteracting CO2 drawdown by silicate weathering and biospheric OC burial.}, language = {en} } @article{BorchardtTrauth2012, author = {Borchardt, Sven and Trauth, Martin H.}, title = {Remotely-sensed evapotranspiration estimates for an improved hydrological modeling of the early holocene mega-lake Suguta, northern Kenya Rift}, series = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, volume = {361}, journal = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, number = {22}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0031-0182}, doi = {10.1016/j.palaeo.2012.07.009}, pages = {14 -- 20}, year = {2012}, abstract = {The actual evapotranspiration is an important, but difficult to determine, element in the water balance of lakes and their catchment areas. Reliable data on evapotranspiration are not available for most lake basins for which paleoclimate reconstructions and modeling have been performed, particularly those in remote parts of Africa. We have used thermal infrared multispectral data for 14 ASTER scenes from the TERRA satellite to estimate the actual evapotranspiration in the 12,800 km(2) catchment of the Suguta Valley, northern Kenya Rift Evidence from sediments and paleo-shorelines indicates that, during the African Humid Period (AHP, 14.8 to 5.5 kyrs BP), this valley contained a large lake, 280 m deep and covering similar to 2200 km(2), which has now virtually disappeared. Evapotranspiration estimates for the Suguta Basin were generated using the Surface Energy Balance Algorithm for Land (SEBAL). Climate data required for the model were extracted from a high-resolution gridded dataset obtained from the Climatic Research Unit (East Anglia, UK). Results suggest significant spatial variations in evapotranspiration within the catchment area (ranging from 450 mm/yr in the basin to the north to 2000 mm/yr in more elevated areas) and precipitation that was similar to 20\% higher during the AHP than in recent times. These results are in agreement with other estimates of paleo-precipitation in East Africa. The extreme response of the lake system (similar to 280 m greater water depth than today, and a lake surface area of 2200 km(2)) to only moderately higher precipitation illustrates the possible sensitivity of this area to future climate change.}, language = {en} } @article{LueckRuehlmann2013, author = {L{\"u}ck, Erika and R{\"u}hlmann, J{\"o}rg}, title = {Resistivity mapping with GEOPHILUS ELECTRICUS - Information about lateral and vertical soil heterogeneity}, series = {Geoderma : an international journal of soil science}, volume = {199}, journal = {Geoderma : an international journal of soil science}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0016-7061}, doi = {10.1016/j.geoderma.2012.11.009}, pages = {2 -- 11}, year = {2013}, abstract = {GEOPHILUS ELECTRICUS (nickname GEOPHILUS) is a novel system for mapping the complex electrical bulk resistivity of soils. Rolling electrodes simultaneously measure amplitude and phase data at frequencies ranging from 1 mHz to 1 kHz. The sensor's design and technical specifications allow for measuring these parameters at five depths of up to ca. 1.5 m. Data inversion techniques can be employed to determine resistivity models instead of apparent values and to image soil layers and their geometry with depth. When used in combination with a global positioning system (GPS) and a suitable cross-country vehicle, it is possible to map about 100 ha/day (assuming 1 data point is recorded per second and the line spacing is 18 m). The applicability of the GEOPHILUS system has been demonstrated on several sites, where soils show variations in texture, stratification, and thus electrical characteristics. The data quality has been studied by comparison with 'static' electrodes, by repeated measurements, and by comparison with other mobile conductivity mapping devices (VERIS3100 and EM38). The high quality of the conductivity data produced by the GEOPHILUS system is evident and demonstrated by the overall consistency of the individual maps, and in the clear stratification also confirmed by independent data. The GEOPHILUS system measures complex values of electrical resistivity in terms of amplitude and phase. Whereas electrical conductivity data (amplitude) are well established in soil science, the interpretation of phase data is a topic of current research. Whether phase data are able to provide additional information depends on the site-specific settings. Here, we present examples, where phase data provide complementary information on man-made structures such as metal pipes and soil compaction.}, language = {en} } @article{StrolloParolaiBindietal.2012, author = {Strollo, Angelo and Parolai, Stefano and Bindi, Dino and Chiauzzi, Leonardo and Pagliuca, Rossella and Mucciarelli, Marco and Zschau, Jochen}, title = {Microzonation of Potenza (Southern Italy) in terms of spectral intensity ratio using joint analysis of earthquakes and ambient noise}, series = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering}, volume = {10}, journal = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering}, number = {2}, publisher = {Springer}, address = {Dordrecht}, issn = {1570-761X}, doi = {10.1007/s10518-011-9256-4}, pages = {493 -- 516}, year = {2012}, abstract = {A temporary seismic network composed of 11 stations was installed in the city of Potenza (Southern Italy) to record local and regional seismicity within the context of a national project funded by the Italian Department of Civil Protection (DPC). Some stations were moved after a certain time in order to increase the number of measurement points, leading to a total of 14 sites within the city by the end of the experiment. Recordings from 26 local earthquakes (M-l 2.2-3.8 ) were analyzed to compute the site responses at the 14 sites by applying both reference and non-reference site techniques. Furthermore, the Spectral Intensity (SI) for each local earthquake, as well as their ratios with respect to the values obtained at a reference site, were also calculated. In addition, a field survey of 233 single station noise measurements within the city was carried out to increase the information available at localities different from the 14 monitoring sites. By using the results of the correlation analysis between the horizontal-to-vertical spectral ratios computed from noise recordings (NHV) at the 14 selected sites and those derived by the single station noise measurements within the town as a proxy, the spectral intensity correction factors for site amplification obtained from earthquake analysis were extended to the entire city area. This procedure allowed us to provide a microzonation map of the urban area that can be directly used when calculating risk scenarios for civil defence purposes. The amplification factors estimated following this approach show values increasing along the main valley toward east where the detrital and alluvial complexes reach their maximum thickness.}, language = {en} } @article{GuillemoteauLueckTronicke2017, author = {Guillemoteau, Julien and L{\"u}ck, Erika and Tronicke, Jens}, title = {1D inversion of direct current data acquired with a rolling electrode system}, series = {Journal of applied geophysics}, volume = {146}, journal = {Journal of applied geophysics}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0926-9851}, doi = {10.1016/j.jappgeo.2017.09.010}, pages = {167 -- 177}, year = {2017}, abstract = {Direct current systems employing a kinematic surveying strategy allow to analyze the electrical resistivity of the subsurface for large areas (i.e., several hectares). Typical applications are found in precision agriculture, archaeological prospecting and soil sciences. With the typical survey setting, the collected data sets are often characterized by a rather high level of noise and a rather coarse lateral sampling compared to data acquired with fixed electrodes. We therefore present an efficient one-dimensional inversion approach in which we put special attention on modeling the effects of noise. We apply this method to data recorded with a five-offset equatorial dipole-dipole system employing rolling electrodes. By performing several synthetic tests with realistic noise levels, we found that the considered five-configuration soundings allow for a reliable imaging of two-layer cases in the uppermost two meters of the subsurface, where the subsurface can be assumed to follow a horizontally layered geometry within 3 m around the system. By analyzing the corresponding sensitivity functions, we also show that the equatorial dipole-dipole array is relatively well suited for a 1D inversion approach compared to standard in-line electrode arrays. To illustrate this aspect, we show that our method can provide results similar to those obtained with a 2D Wenner imaging procedure for data recorded across a well-constrained 2D target. We finally apply our method to a large five-offset data set acquired in an agricultural study. The final pseudo-3D model of electrical resistivity is in accordance with borehole data available for the surveyed area. Our results demonstrate the applicability and the versatility of the presented inversion approach for large-scale data sets as they are typically collected with such rolling electrode systems. (C) 2017 Elsevier B.V. All rights reserved.}, language = {en} } @article{LueckMueller2009, author = {L{\"u}ck, Erika and M{\"u}ller, Martin}, title = {Special section on the application of geophysics in agriculture : part II ; foreword}, issn = {1569-4445}, year = {2009}, language = {en} } @article{LueckGebbersRuehlmannetal.2009, author = {L{\"u}ck, Erika and Gebbers, Robin and Ruehlmann, Joerg and Spangenberg, Ulrike}, title = {Electrical conductivity mapping for precision farming}, issn = {1569-4445}, doi = {10.3997/1873-0604.2008031}, year = {2009}, abstract = {Precision farming overcomes the paradigm of uniform field treatment by site-specific data acquisition and treatment to cope with within-field variability. Precision farming heavily relies on spatially dense information about soil and crop status. While it is often difficult and expensive to obtain precise soil information by traditional soil sampling and laboratory analysis some geophysical methods offer means to obtain subsidiary data in an efficient way. In particular, geoelectrical soil mapping has become widely accepted in precision farming. At present it is the most successful geophysical method providing the spatial distribution of relevant agronomic information that enables us to determine management zones for precision farming. Much work has been done to test the applicability of existing geoelectrical methods and to develop measurement systems applicable in the context of precision farming. Therefore, the aim of this paper was to introduce the basic ideas of precision farming, to discuss current precision farming applied geoelectrical methods and instruments and to give an overview about our corresponding activities during recent years. Different experiments were performed both in the laboratory and in the field to estimate first, electrical conductivity affecting factors, second, relationships between direct push and surface measurements, third, the seasonal stability of electrical conductivity patterns and fourth, the relationship between plant yield and electrical conductivity. From the results of these experiments, we concluded that soil texture is a very dominant factor in electrical conductivity mapping. Soil moisture affects both the level and the dynamic range of electrical conductivity readings. Nevertheless, electrical conductivity measurements can be principally performed independent of season. However, electrical conductivity field mapping does not produce reliable maps of spatial particle size distribution of soils, e.g., necessary to generate input parameters for water and nutrient transport models. The missing step to achieve this aim may be to develop multi-sensor systems that allow adjusting the electrical conductivity measurement from the influence of different soil water contents.}, language = {en} } @article{PicozziStrolloParolaietal.2009, author = {Picozzi, Matteo and Strollo, Angelo and Parolai, Stefano and Durukal, Eser and oezel, Oguz and Karabulut, Savas and Zschau, Jochen and Erdik, Mustafa}, title = {Site characterization by seismic noise in Istanbul, Turkey}, issn = {0267-7261}, doi = {10.1016/j.soildyn.2008.05.007}, year = {2009}, abstract = {Single station seismic noise measurements were carried out at 192 sites in the western part of Istanbul, Turkey. This extensive survey allowed the fundamental resonance frequency of the sedimentary cover to be mapped, and identify areas prone to site amplification. The results are in good agreement with the geological distribution of sedimentary units, indicating a progressive decrease of the fundamental resonance frequencies from the northeastern part, where the bedrock outcrops, towards the southwestern side, where a thickness of some hundreds meters for the sedimentary cover is estimated. The particular distribution of fundamental resonance frequencies indicates that local amplification of the ground motion might play a significative role in explaining the anomalous damage distribution after the 17 August 1999 Kocaeli Earthquake. Furthermore, 2D array measurements of seismic noise were performed in the metropolitan area with the aim of obtaining a preliminary geophysical characterization of the different sedimentary covers. These measurements allow the estimation of the shear-wave velocity profile for some representative areas and the identification of the presence of strong impedance contrast responsible of seismic ground motion amplification. Comparison of a theoretical site response from an estimated S-wave velocity profile with an empirical one based on earthquake recordings strongly encourages the use of the low cost seismic noise techniques for the study of seismic site effects.}, language = {en} } @article{PicozziParolaiBindietal.2009, author = {Picozzi, Matteo and Parolai, Stefano and Bindi, Dino and Strollo, Angelo}, title = {Characterization of shallow geology by high-frequency seismic noise tomography}, issn = {0956-540X}, doi = {10.1111/j.1365-246X.2008.03966.x}, year = {2009}, abstract = {To study the applicability of the passive seismic interferometry technique to near-surface geological studies, seismic noise recordings from a small scale 2-D array of seismic stations were performed in the test site of Nauen (Germany). Rayleigh wave Green's functions were estimated for different frequencies. A tomographic inversion of the traveltimes estimated for each frequency from the Green's functions is then performed, allowing the laterally varying 3-D surfacewave velocity structure below the array to be retrieved at engineering-geotechnical scales. Furthermore, a 2-D S-wave velocity cross-section is obtained by combining 1-D velocity structures derived from the inversion of the dispersion curves extracted at several points along a profile where other geophysical analyses were performed. It is shown that the cross-section from passive seismic interferometry provides a clear image of the local structural heterogeneities that are in excellent agreement with georadar and geoelectrical results. Such findings indicate that the interferometry analysis of seismic noise is potentially of great interest for deriving the shallow 3-D velocity structure in urban areas.}, language = {en} } @article{DiGiacomoBindiParolaietal.2011, author = {Di Giacomo, Domenico and Bindi, Dino and Parolai, Stefano and Oth, Adrien}, title = {Residual analysis of teleseismic P-wave energy magnitude estimates: inter- and intrastation variability}, series = {Geophysical journal international}, volume = {185}, journal = {Geophysical journal international}, number = {3}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0956-540X}, doi = {10.1111/j.1365-246X.2011.05019.x}, pages = {1444 -- 1454}, year = {2011}, abstract = {P>Computing the magnitude of an earthquake requires correcting for the propagation effects from the source to the receivers. This is often accomplished by performing numerical simulations using a suitable Earth model. In this work, the energy magnitude M(e) is considered and its determination is performed using theoretical spectral amplitude decay functions over teleseismic distances based on the global Earth model AK135Q. Since the high frequency part (above the corner frequency) of the source spectrum has to be considered in computing M(e), the influence of propagation and site effects may not be negligible and they could bias the single station M(e) estimations. Therefore, in this study we assess the inter- and intrastation distributions of errors by considering the M(e) residuals computed for a large data set of earthquakes recorded at teleseismic distances by seismic stations deployed worldwide. To separate the inter- and intrastation contribution of errors, we apply a maximum likelihood approach to the M(e) residuals. We show that the interstation errors (describing a sort of site effect for a station) are within +/- 0.2 magnitude units for most stations and their spatial distribution reflects the expected lateral variation affecting the velocity and attenuation of the Earth's structure in the uppermost layers, not accounted for by the 1-D AK135Q model. The variance of the intrastation error distribution (describing the record-to-record component of variability) is larger than the interstation one (0.240 against 0.159), and the spatial distribution of the errors is not random but shows specific patterns depending on the source-to-station paths. The set of coefficients empirically determined may be used in the future to account for the heterogeneities of the real Earth not considered in the theoretical calculations of the spectral amplitude decay functions used to correct the recorded data for propagation effects.}, language = {en} } @article{WalterHamannLuecketal.2016, author = {Walter, J. and Hamann, G{\"o}ran and L{\"u}ck, Erika and Klingenfuss, C. and Zeitz, Jutta}, title = {Stratigraphy and soil properties of fens: Geophysical case studies from northeastern Germany}, series = {Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution}, volume = {142}, journal = {Catena : an interdisciplinary journal of soil science, hydrology, geomorphology focusing on geoecology and landscape evolution}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0341-8162}, doi = {10.1016/j.catena.2016.02.028}, pages = {112 -- 125}, year = {2016}, abstract = {The determination of the total carbon storage of peatlands is of high relevance in the context of climate-change mitigation efforts. This determination relies on data about stratigraphy and peat properties, which are conventionally collected by coring. Ground-penetrating radar (GPR) and electrical resistivity imaging (ERI) can support these point data by providing subsoil information in two-dimensional cross-sections. In this study, GPR and ERI were conducted at two groundwater-fed fen sites located in the temperate zone in north-east Germany. The fens of this region are embedded in low conductive glacial sand and are characterised by thick layers of gyttja, which can be either mineral or organic. The two study sites are representative of this region with respect to stratigraphy (total thickness, peat and gyttja types) and ecological conditions (pH-value, trophic condition). The aim of this study is to assess the suitability of GPR and ERI to detect stratigraphy and peat properties under these characteristic site conditions. Results show that GPR clearly detects the interfaces between (i) Carex and brown-moss peat, (ii) brown-moss peat and organic gyttja, (iii) organic- and mineral gyttja, and (iv) mineral gyttja and the parent material (glacial sand). These layers differ in bulk density and the related organic matter content. ERI, however, does not delineate these layers; rather it delineates regions of varying properties. At our base-rich site, pore fluid conductivity and cation.exchange capacity are the main factors that determine peat electrical conductivity (reverse of resistivity), whereas organic matter and water content are most influential at the more acidic site. Thus the correlation between peat properties and electrical conductivity are driven by site-specific conditions, which are mainly determined by the solute load in the groundwater at fens. When the total organic deposits exceed a thickness of 5 m, the depth of investigation by GPR is limited due to increasing attenuation. This is not a limiting factor for ERI, where the transition from organic deposits to glacial sand is visible at both sites. Due to these specific sensitivities, a combined application of GPR and ERI meets the demand for up-to-date information on carbon storage of peatlands, which is, moreover, very site-specific because of the inherent variety of ecological conditions and stratigraphy between peatlands in general and between fens and bogs in particular. (C) 2016 Elsevier B.V. All rights reserved.}, language = {en} } @article{GuillemoteauSimonLuecketal.2016, author = {Guillemoteau, Julien and Simon, Francois-Xavier and L{\"u}ck, Erika and Tronicke, Jens}, title = {1D sequential inversion of portable multi-configuration electromagnetic induction data}, series = {Near surface geophysics}, volume = {14}, journal = {Near surface geophysics}, publisher = {Wiley-VCH}, address = {Houten}, issn = {1569-4445}, doi = {10.3997/1873-0604.2016029}, pages = {423 -- 432}, year = {2016}, abstract = {We present an algorithm that performs sequentially one-dimensional inversion of subsurface magnetic permeability and electrical conductivity by using multi-configuration electromagnetic induction sensor data. The presented method is based on the conversion of the in-phase and out-of-phase data into effective magnetic permeability and electrical conductivity of the equivalent homogeneous half-space. In the case of small-offset systems, such as portable electromagnetic induction sensors, for which in-phase and out-of-phase data are moderately coupled, the effective half-space magnetic permeability and electrical conductivity can be inverted sequentially within an iterative scheme. We test and evaluate the proposed inversion strategy using synthetic and field examples. First, we apply it to synthetic data for some highly magnetic environments. Then, the method is tested on real field data acquired in a basaltic environment to image a formation of archaeological interest. These examples demonstrate that a joint interpretation of in-phase and out-of-phase data leads to a better characterisation of the subsurface in magnetic environments such as volcanic areas.}, language = {en} } @article{ParolaiAnsalKurtulusetal.2009, author = {Parolai, Stefano and Ansal, Atilla and Kurtulus, Asil and Strollo, Angelo and Wang, Rongjiang and Zschau, Jochen}, title = {The Atakoey vertical array (Turkey) : insights into seismic wave propagation in the shallow-most crustal layers by waveform deconvolution}, issn = {0956-540X}, doi = {10.1111/j.1365-246X.2009.04257.x}, year = {2009}, abstract = {P>A vertical array of accelerometers was installed in Atakoy (western Istanbul) with the long-term aim of improving our understanding of in situ soil behaviour, to assess the modelling and parametric uncertainties associated with the employed methodologies for strong-motion site-response analysis, and for shallow geological investigations. Geotechnical and geophysical investigations were carried out to define the subsoil structure at the selected site. Data associated with 10 earthquakes (2.7 < M < 4.3) collected during the first months of operation of the array were used to image the upgoing and downgoing waves by deconvolution of waveforms recorded at different depths. Results have shown that the velocity of propagation of the imaged upgoing and downgoing waves in the borehole is consistent with that of S or P waves, depending on the component of ground acceleration analysed but independent of the chosen signal window. In particular, an excellent agreement was found between the observed upgoing and downgoing wave traveltimes and the ones calculated using a model derived by seismic noise analysis of array data. The presence of a smaller pulse on the waveforms obtained by deconvolution of the horizontal components suggests both internal S-wave reflection and S-to-P mode conversion, as well as a not normal incidence of the wavefield. The presence of a pulse propagating with S-wave velocity in the uppermost 25 m in the waveforms obtained by the deconvolution of the vertical components suggests P-to-S mode conversion. These evidences imply that, even when site amplification is mainly related to 1-D effects, the standard practice in engineering seismology of deconvolving the surface recording down to the bedrock using an approximate S-wave transfer function (generally valid for vertical incidence of SH waves) might lead to errors in the estimation of the input ground motion required in engineering calculations. Finally, downgoing waves with significant amplitudes were found down to 70 m and even to 140 m depth. This result provides a warning about the use of shallow borehole recordings as input for the numerical simulation of ground motion and for the derivation of ground motion prediction relationships.}, language = {en} } @article{OverduinHaberlandRybergetal.2015, author = {Overduin, Pier Paul and Haberland, Christian and Ryberg, Trond and Kneier, Fabian and Jacobi, Tim and Grigoriev, Mikhail N. and Ohrnberger, Matthias}, title = {Submarine permafrost depth from ambient seismic noise}, series = {Geophysical research letters}, volume = {42}, journal = {Geophysical research letters}, number = {18}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1002/2015GL065409}, pages = {7581 -- 7588}, year = {2015}, abstract = {Permafrost inundated since the last glacial maximum is degrading, potentially releasing trapped or stabilized greenhouse gases, but few observations of the depth of ice-bonded permafrost (IBP) below the seafloor exist for most of the arctic continental shelf. We use spectral ratios of the ambient vibration seismic wavefield, together with estimated shear wave velocity from the dispersion curves of surface waves, for estimating the thickness of the sediment overlying the IBP. Peaks in spectral ratios modeled for three-layered 1-D systems correspond with varying thickness of the unfrozen sediment. Seismic receivers were deployed on the seabed around Muostakh Island in the central Laptev Sea, Siberia. We derive depths of the IBP between 3.7 and 20.7m15\%, increasing with distance from the shoreline. Correspondence between expected permafrost distribution, modeled response, and observational data suggests that the method is promising for the determination of the thickness of unfrozen sediment.}, language = {en} } @article{KonradSchmolkeZackO'Brien2009, author = {Konrad-Schmolke, Matthias and Zack, Thomas and O'Brien, Patrick J.}, title = {Combining thermodynamic and trace element modeling : a tool to quantify mineral reactions and trace element budgets during metamorphism}, issn = {0016-7037}, doi = {10.1016/j.gca.2009.05.009}, year = {2009}, language = {en} } @article{KonradSchmolkeO'BrienZack2011, author = {Konrad-Schmolke, Matthias and O'Brien, Patrick J. and Zack, Thomas}, title = {Fluid Migration above a Subducted Slab-Constraints on Amount, Pathways and Major Element Mobility from Partially Overprinted Eclogite-facies Rocks (Sesia Zone, Western Alps)}, series = {Journal of petrology}, volume = {52}, journal = {Journal of petrology}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0022-3530}, doi = {10.1093/petrology/egq087}, pages = {457 -- 486}, year = {2011}, abstract = {The Western Alpine Sesia-Lanzo Zone (SLZ) is a sliver of eclogite-facies continental crust exhumed from mantle depths in the hanging wall of a subducted oceanic slab. Eclogite-facies felsic and basic rocks sampled across the internal SLZ show different degrees of retrograde metamorphic overprint associated with fluid influx. The weakly deformed samples preserve relict eclogite-facies mineral assemblages that show partial fluid-induced compositional re-equilibration along grain boundaries, brittle fractures and other fluid pathways. Multiple fluid influx stages are indicated by replacement of primary omphacite by phengite, albitic plagioclase and epidote as well as partial re-equilibration and/or overgrowths in phengite and sodic amphibole, producing characteristic step-like compositional zoning patterns. The observed textures, together with the map-scale distribution of the samples, suggest open-system, pervasive and reactive fluid flux across large rock volumes above the subducted slab. Thermodynamic modelling indicates a minimum amount of fluid of 0 center dot 1-0 center dot 5 wt \% interacting with the wall-rocks. Phase relations and reaction textures indicate mobility of K, Ca, Fe and Mg, whereas Al is relatively immobile in these medium-temperature-high-pressure fluids. Furthermore, the thermodynamic models show that recycling of previously fractionated material, such as in the cores of garnet porphyroblasts, largely controls the compositional re-equilibration of the exhumed rock body.}, language = {en} } @article{KonradSchmolkeZackO'Brienetal.2011, author = {Konrad-Schmolke, Matthias and Zack, Thomas and O'Brien, Patrick J. and Barth, Matthias}, title = {Fluid migration above a subducted slab - Thermodynamic and trace element modelling of fluid-rock interaction in partially overprinted eclogite-facies rocks (Sesia Zone, Western Alps)}, series = {Earth \& planetary science letters}, volume = {311}, journal = {Earth \& planetary science letters}, number = {3-4}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0012-821X}, doi = {10.1016/j.epsl.2011.09.025}, pages = {287 -- 298}, year = {2011}, abstract = {The amount and composition of subduction zone fluids and the effect of fluid-rock interaction at a slab-mantle interface have been constrained by thermodynamic and trace element modelling of partially overprinted blueschist-facies rocks from the Sesia Zone (Western Alps). Deformation-induced differences in fluid flux led to a partial preservation of pristine mineral cores in weakly deformed samples that were used to quantify Li, B, Stand Pb distribution during mineral growth, -breakdown and modification induced by fluid-rock interaction. Our results show that Li and 13 budgets are fluid-controlled, thus acting as tracers for fluid-rock interaction processes, whereas Stand Pb budgets are mainly controlled by the fluid-induced formation of epidote. Our calculations show that fluid-rock interaction caused significant Li and B depletion in the affected rocks due to leaching effects, which in turn can lead to a drastic enrichment of these elements in the percolating fluid. Depending on available fluid-mineral trace element distribution coefficients modelled fluid rock ratios were up to 0.06 in weakly deformed samples and at least 0.5 to 4 in shear zone mylonites. These amounts lead to time integrated fluid fluxes of up to 1.4-10(2) m(3) m(-2) in the weakly deformed rocks and 1-8-10(3) m(3) m(-2) in the mylonites. Combined thermodynamic and trace element models can be used to quantify metamorphic fluid fluxes and the associated element transfer in complex, reacting rock systems and help to better understand commonly observed fluid-induced trace element trends in rocks and minerals from different geodynamic environments.}, language = {en} } @article{SchmidtMezgerO'Brien2011, author = {Schmidt, Alexander and Mezger, Klaus and O'Brien, Patrick J.}, title = {The time of eclogite formation in the ultrahigh pressure rocks of the Sulu terrane Constraints from Lu-Hf garnet geochronology}, series = {Lithos : an international journal of mineralogy, petrology, and geochemistry}, volume = {125}, journal = {Lithos : an international journal of mineralogy, petrology, and geochemistry}, number = {1-2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0024-4937}, doi = {10.1016/j.lithos.2011.04.004}, pages = {743 -- 756}, year = {2011}, abstract = {Eclogites from the main borehole of the Chinese Continental Scientific Drilling project yield highly precise Lu-Hf garnet-clinopyroxene ages of 216.9 +/- 1.2 Ma (four samples) and 220.5 +/- 2.7 Ma (one sample). The spatial distribution of the rare earth elements in garnet is consistent with the preservation of primary growth zoning, unmodified by diffusion, which supports the interpretation that the Lu-Hf ages date the time of formation of garnet, the major rock forming mineral in the eclogites. The preservation of primary REE-zoning, despite peak metamorphic temperatures around 800-850 degrees C. indicates that the Lu-Hf chronometer is perfectly suitable to date garnet-forming reactions in high grade rocks. The range of Lu-Hf ages for eclogites in the Dabie-Sulu UHP terrane point to episodic rather than continuous growth of garnets and thus punctuated metamorphism during the collision of the North China Block and the Yangtze Block. The U-Pb ages and Hf-isotope systematics of zircon grains from one eclogite sample imply a protracted geologic history of the eclogite precursors that started around 2 Ga and culminated in the UHP metamorphism around 220 Ma.}, language = {en} } @article{KotkovaO'BrienZiemann2011, author = {Kotkova, Jana and O'Brien, Patrick J. and Ziemann, Martin Andreas}, title = {Diamond and coesite discovered in Saxony-type granulite solution to the Variscan garnet peridotite enigma}, series = {Geology}, volume = {39}, journal = {Geology}, number = {7}, publisher = {American Institute of Physics}, address = {Boulder}, issn = {0091-7613}, doi = {10.1130/G31971.1}, pages = {667 -- 670}, year = {2011}, abstract = {The pressures required for diamond and coesite formation far exceed conditions reached by even the deepest present-day orogenic crustal roots. Therefore the occurrence of metamorphosed continental crust containing these minerals requires processes other than crustal thickening to have operated in the past. Here we report the first in situ finding of diamond and coesite, characterized by micro-Raman spectroscopy, in high-pressure granulites otherwise indistinguishable from granulites found associated with garnet peridotite throughout the European Variscides. Our discovery confirms the provenance of Europe's first reliable diamond, the "Bohemian diamond," found in A.D. 1870, and also represents the first robust evidence for ultrahigh-pressure conditions in a major Variscan crustal rock type. A process of deep continental subduction is required to explain the metamorphic pressures and the granulite-garnet peridotite association, and thus tectonometamorphic models for these rocks involving a deep orogenic crustal root need to be significantly modified.}, language = {en} } @article{SchertlO'Brien2013, author = {Schertl, Hans-Peter and O'Brien, Patrick}, title = {Continental crust at mantle depths - key minerals and microstructures}, series = {Elements : an international magazine of mineralogy, geochemistry, and petrology}, volume = {9}, journal = {Elements : an international magazine of mineralogy, geochemistry, and petrology}, number = {4}, publisher = {Mineralogical Society of America}, address = {Chantilly}, issn = {1811-5209}, doi = {10.2113/gselements.9.4.261}, pages = {261 -- 266}, year = {2013}, abstract = {Finding evidence for ultrahigh-pressure (UHP) metamorphism in crustal rocks is far from straightforward. The index minerals coesite and diamond are incredibly inconspicuous and are therefore difficult to use as UHP prospecting tools. Consequently, petrographers rely on recognizing subtle breakdown microstructures that result from pressure release during the return to the surface of the once deeply buried rock. Similarly, many other UHP minerals are first suspected on the basis of typical reaction or exsolution microstructures. Thus, the painstaking use of microscopic techniques has been fundamental to the tremendous advances in characterizing, quantifying, and understanding macroscopic-scale, deep continental subduction, rapid exhumation, and mountain-building processes.}, language = {en} } @article{RegenbergStephNuernbergetal.2009, author = {Regenberg, Marcus and Steph, Silke and Nuernberg, Dirk and Tiedemann, Ralph and Garbe-Schoenberg, Dieter}, title = {Calibrating Mg/Ca ratios of multiple planktonic foraminiferal species with delta O-18-calcification temperatures : paleothermometry for the upper water column}, issn = {0012-821X}, doi = {10.1016/j.epsl.2008.12.019}, year = {2009}, abstract = {In order to consistently approximate the thermal vertical structure of past upper water columns, Mg/Ca ratios of eight planktonic foraminiferal species with different preferential calcification depths selected from 76 tropical Atlantic and Caribbean sediment-surface samples were calibrated with delta O-18-derived calcification temperatures with an overall range of approximate to 8-28 degrees C. Extending the broad number of species-specific calibrations, which agree well especially with our shallow-dweller calibrations, this study presents new bulk calcite Mg/Ca vs. calcification temperature relationships for shallow-dwelling Globigerinoides ruber pink, thermocline-dwelling Globorotalia menardii, and deep-dwelling Globorotalia truncatulinoides dextral and Globorotalia crassaformis not separately calibrated before. The species-specific temperature sensitivities are relatively similar (approximate to 7- 11\% increase in Mg/Ca per 1 degrees C), yet y-axis intercepts vary from 0.23-0.65 for the shallow and thermocline dwellers to 0.83-1.32 for the deep dwellers. Based on these differences, we established a 'warm water' calibration for temperatures > 19 degrees C (Mg/Ca=0.29.exp(0.101.T): r=0.90; shallow and thermocline dwellers) and a 'cold water' calibration for temperatures < 15 degrees C (Mg/Ca=0.84.exp(0.083.T); r=0.85; deep dwellers). These calibrations are offset by approximate to 8 degrees C. This maybe significant for paleotemperature reconstructions, which are afflicted with the problem that similar Mg/Ca offsets are probably characteristic of extinct species used to calculate past temperatures.}, language = {en} } @article{TiedemannSchneiderHavensteinetal.2014, author = {Tiedemann, Ralph and Schneider, Anja R. R. and Havenstein, Katja and Blanck, Torsten and Meier, Elmar and Raffel, Martina and Zwartepoorte, Henk and Plath, Martin}, title = {New microsatellite markers allow high-resolution taxon delimitation in critically endangered Asian box turtles, genus Cuora}, series = {Salamandra : German journal of herpetology}, volume = {50}, journal = {Salamandra : German journal of herpetology}, number = {3}, publisher = {Deutsche Gesellschaft f{\"u}r Herpetologie und Terrarienkunde}, address = {Darmstadt}, issn = {0036-3375}, pages = {139 -- 146}, year = {2014}, abstract = {We isolated and characterized 16 new di- and tetranudeotide microsatellite markers for the critically endangered Asian box turtle genus Cuora, focusing on the "Cuora trifasciata" species complex. The new markers were then used to analyse genetic variability and divergence amongst five described species within this complex, namely C. aurocapitata (n = 18), C. cyclornata (n = 31), C. pani (n = 6), C. trifasciata (n = 58), and C. zhoui (n = 7). Our results support the view that all five species represent valid taxa. Within two species (C. trifasciata and C. cyclornata), two distinct morphotypes were corroborated by microsatellite divergence. For three individuals, morphologically identified as being of hybrid origin, the hybrid status was confirmed by our genetic analysis. Our results confirm the controversial species (Cuora aurocapitata, C. cyclornata) and subspecies/morphotypes (C. cyclornata meieri, C. trifasciata cf. trifasciata) to be genetically distinct, which has critical implications for conservation strategies.}, language = {en} } @phdthesis{Wulf2011, author = {Wulf, Hendrik}, title = {Seasonal precipitation, river discharge, and sediment flux in the western Himalaya}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-57905}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {Rainfall, snow-, and glacial melt throughout the Himalaya control river discharge, which is vital for maintaining agriculture, drinking water and hydropower generation. However, the spatiotemporal contribution of these discharge components to Himalayan rivers is not well understood, mainly because of the scarcity of ground-based observations. Consequently, there is also little known about the triggers and sources of peak sediment flux events, which account for extensive hydropower reservoir filling and turbine abrasion. We therefore lack basic information on the distribution of water resources and controls of erosion processes. In this thesis, I employ various methods to assess and quantify general characteristics of and links between precipitation, river discharge, and sediment flux in the Sutlej Valley. First, I analyze daily precipitation data (1998-2007) from 80 weather stations in the western Himalaya, to decipher the distribution of rain- and snowfall. Rainfall magnitude frequency analyses indicate that 40\% of the summer rainfall budget is attributed to monsoonal rainstorms, which show higher variability in the orogenic interior than in frontal regions. Combined analysis of rainstorms and sediment flux data of a major Sutlej River tributary indicate that monsoonal rainfall has a first order control on erosion processes in the orogenic interior, despite the dominance of snowfall in this region. Second, I examine the contribution of rainfall, snow and glacial melt to river discharge in the Sutlej Valley (s55,000 km2), based on a distributed hydrological model, which covers the period 2000-2008. To achieve high spatial and daily resolution despite limited ground-based observations the hydrological model is forced by daily remote sensing data, which I adjusted and calibrated with ground station data. The calibration shows that the Tropical Rainfall Measuring Mission (TRMM) 3B42 rainfall product systematically overestimates rainfall in semi-arid and arid regions, increasing with aridity. The model results indicate that snowmelt-derived discharge (74\%) is most important during the pre-monsoon season (April to June) whereas rainfall (56\%) and glacial melt (17\%) dominate the monsoon season (July-September). Therefore, climate change most likely causes a reduction in river discharge during the pre-monsoon season, which especially affects the orogenic interior. Third, I investigate the controls on suspended sediment flux in different parts of the Sutlej catchments, based on daily gauging data from the past decade. In conjunction with meteorological data, earthquake records, and rock strength measurements I find that rainstorms are the most frequent trigger of high-discharge events with peaks in suspended sediment concentrations (SSC) that account for the bulk of the suspended sediment flux. The suspended sediment flux increases downstream, mainly due to increases in runoff. Pronounced erosion along the Himalayan Front occurs throughout the monsoon season, whereas efficient erosion of the orogenic interior is confined to single extreme events. The results of this thesis highlight the importance of snow and glacially derived melt waters in the western Himalaya, where extensive regions receive only limited amounts of monsoonal rainfall. These regions are therefore particularly susceptible to global warming with major implications on the hydrological cycle. However, the sediment discharge data show that infrequent monsoonal rainstorms that pass the orographic barrier of the Higher Himalaya are still the primary trigger of the highest-impact erosion events, despite being subordinate to snow and glacially-derived discharge. These findings may help to predict peak sediment flux events and could underpin the strategic development of preventative measures for hydropower infrastructures.}, language = {en} } @phdthesis{Mohr2013, author = {Mohr, Christian Heinrich}, title = {Hydrological and erosion responses to man-made and natural disturbances : insights from forested catchments in South-central Chile}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70146}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Logging and large earthquakes are disturbances that may significantly affect hydrological and erosional processes and process rates, although in decisively different ways. Despite numerous studies that have documented the impacts of both deforestation and earthquakes on water and sediment fluxes, a number of details regarding the timing and type of de- and reforestation; seismic impacts on subsurface water fluxes; or the overall geomorphic work involved have remained unresolved. The main objective of this thesis is to address these shortcomings and to better understand and compare the hydrological and erosional process responses to such natural and man-made disturbances. To this end, south-central Chile provides an excellent natural laboratory owing to its high seismicity and the ongoing conversion of land into highly productive plantation forests. In this dissertation I combine paired catchment experiments, data analysis techniques, and physics-based modelling to investigate: 1) the effect of plantation forests on water resources, 2) the source and sink behavior of timber harvest areas in terms of overland flow generation and sediment fluxes, 3) geomorphic work and its efficiency as a function of seasonal logging, 4) possible hydrologic responses of the saturated zone to the 2010 Maule earthquake and 5) responses of the vadose zone to this earthquake. Re 1) In order to quantify the hydrologic impact of plantation forests, it is fundamental to first establish their water balances. I show that tree species is not significant in this regard, i.e. Pinus radiata and Eucalyptus globulus do not trigger any decisive different hydrologic response. Instead, water consumption is more sensitive to soil-water supply for the local hydro-climatic conditions. Re 2) Contradictory opinions exist about whether timber harvest areas (THA) generate or capture overland flow and sediment. Although THAs contribute significantly to hydrology and sediment transport because of their spatial extent, little is known about the hydrological and erosional processes occurring on them. I show that THAs may act as both sources and sinks for overland flow, which in turn intensifies surface erosion. Above a rainfall intensity of ~20 mm/h, which corresponds to <10\% of all rainfall, THAs may generate runoff whereas below that threshold they remain sinks. The overall contribution of Hortonian runoff is thus secondary considering the local rainfall regime. The bulk of both runoff and sediment is generated by Dunne, saturation excess, overland flow. I also show that logging may increase infiltrability on THAs which may cause an initial decrease in streamflow followed by an increase after the groundwater storage has been refilled. Re 3) I present changes in frequency-magnitude distributions following seasonal logging by applying Quantile Regression Forests at hitherto unprecedented detail. It is clearly the season that controls the hydro-geomorphic work efficiency of clear cutting. Logging, particularly dry seasonal logging, caused a shift of work efficiency towards less flashy and mere but more frequent moderate rainfall-runoff events. The sediment transport is dominated by Dunne overland flow which is consistent with physics-based modelling using WASA-SED. Re 4) It is well accepted that earthquakes may affect hydrological processes in the saturated zone. Assuming such flow conditions, consolidation of saturated saprolitic material is one possible response. Consolidation raises the hydraulic gradients which may explain the observed increase in discharge following earthquakes. By doing so, squeezed water saturates the soil which in turn increases the water accessible for plant transpiration. Post-seismic enhanced transpiration is reflected in the intensification of diurnal cycling. Re 5) Assuming unsaturated conditions, I present the first evidence that the vadose zone may also respond to seismic waves by releasing pore water which in turn feeds groundwater reservoirs. By doing so, water tables along the valley bottoms are elevated thus providing additional water resources to the riparian vegetation. By inverse modelling, the transient increase in transpiration is found to be 30-60\%. Based on the data available, both hypotheses, are not testable. Finally, when comparing the hydrological and erosional effects of the Maule earthquake with the impact of planting exotic plantation forests, the overall observed earthquake effects are comparably small, and limited to short time scales.}, language = {en} } @phdthesis{Nikolaeva2013, author = {Nikolaeva, Elena}, title = {Landslide kinematics and interactions studied in central Georgia by using synthetic aperture radar interferometry, optical imagery and inverse modeling}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70406}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Landslides are one of the biggest natural hazards in Georgia, a mountainous country in the Caucasus. So far, no systematic monitoring and analysis of the dynamics of landslides in Georgia has been made. Especially as landslides are triggered by extrinsic processes, the analysis of landslides together with precipitation and earthquakes is challenging. In this thesis I describe the advantages and limits of remote sensing to detect and better understand the nature of landslide in Georgia. The thesis is written in a cumulative form, composing a general introduction, three manuscripts and a summary and outlook chapter. In the present work, I measure the surface displacement due to active landslides with different interferometric synthetic aperture radar (InSAR) methods. The slow landslides (several cm per year) are well detectable with two-pass interferometry. In same time, the extremely slow landslides (several mm per year) could be detected only with time series InSAR techniques. I exemplify the success of InSAR techniques by showing hitherto unknown landslides, located in the central part of Georgia. Both, the landslide extent and displacement rate is quantified. Further, to determine a possible depth and position of potential sliding planes, inverse models were developed. Inverse modeling searches for parameters of source which can create observed displacement distribution. I also empirically estimate the volume of the investigated landslide using displacement distributions as derived from InSAR combined with morphology from an aerial photography. I adapted a volume formula for our case, and also combined available seismicity and precipitation data to analyze potential triggering factors. A governing question was: What causes landslide acceleration as observed in the InSAR data? The investigated area (central Georgia) is seismically highly active. As an additional product of the InSAR data analysis, a deformation area associated with the 7th September Mw=6.0 earthquake was found. Evidences of surface ruptures directly associated with the earthquake could not be found in the field, however, during and after the earthquake new landslides were observed. The thesis highlights that deformation from InSAR may help to map area prone landslides triggering by earthquake, potentially providing a technique that is of relevance for country wide landslide monitoring, especially as new satellite sensors will emerge in the coming years.}, language = {en} } @phdthesis{Kalbe2016, author = {Kalbe, Johannes}, title = {Stepping stones hominin dispersal out of Africa}, school = {Universit{\"a}t Potsdam}, pages = {122}, year = {2016}, language = {en} } @phdthesis{Simon2016, author = {Simon, Sebastian}, title = {Der Einfluss der Koordination von Spurenelementen in silikatischen und aluminosilikatischen Schmelzen auf Elementverteilungsprozesse in magmatischen Systemen}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-100932}, school = {Universit{\"a}t Potsdam}, pages = {xviii, 138}, year = {2016}, abstract = {Das Wissen um die lokale Struktur von Seltenen Erden Elementen (SEE) in silikatischen und aluminosilikatischen Schmelzen ist von fundamentalem Interesse f{\"u}r die Geochemie der magmatischen Prozesse, speziell wenn es um ein umfassendes Verst{\"a}ndnis der Verteilungsprozesse von SEE in magmatischen Systemen geht. Es ist allgemein akzeptiert, dass die SEE-Verteilungsprozesse von Temperatur, Druck, Sauerstofffugazit{\"a}t (im Fall von polyvalenten Kationen) und der Kristallchemie kontrolliert werden. Allerdings ist wenig {\"u}ber den Einfluss der Schmelzzusammensetzung selbst bekannt. Ziel dieser Arbeit ist, eine Beziehung zwischen der Variation der SEE-Verteilung mit der Schmelzzusammensetzung und der Koordinationschemie dieser SEE in der Schmelze zu schaffen. Dazu wurden Schmelzzusammensetzungen von Prowatke und Klemme (2005), welche eine deutliche {\"A}nderung der Verteilungskoeffizienten zwischen Titanit und Schmelze ausschließlich als Funktion der Schmelzzusammensetzung zeigen, sowie haplogranitische bzw. haplobasaltische Schmelzzusammensetzungen als Vertreter magmatischer Systeme mit La, Gd, Yb und Y dotiert und als Glas synthetisiert. Die Schmelzen variierten systematisch im Aluminiums{\"a}ttigungsindex (ASI), welcher bei den Prowatke und Klemme (2005) Zusammensetzungen einen Bereich von 0.115 bis 0.768, bei den haplogranitischen Zusammensetzungen einen Bereich von 0.935 bis 1.785 und bei den haplobasaltischen Zusammensetzungen einen Bereich von 0.368 bis 1.010 abdeckt. Zus{\"a}tzlich wurden die haplogranitischen Zusammensetzungen mit 4 \% H2O synthetisiert, um den Einfluss von Wasser auf die lokale Umgebung von SEE zu studieren. Um Informationen {\"u}ber die lokalen Struktur von Gd, Yb und Y zu erhalten wurde die R{\"o}ntgenabsorptionsspektroskopie angewendet. Dabei liefert die Untersuchung der Feinstruktur mittels der EXAFS-Spektroskopie (engl. Extended X-Ray Absorption Fine Structure) quantitative Informationen {\"u}ber die lokale Umgebung, w{\"a}hrend RIXS (engl. resonant inelastic X-ray scattering), sowie die daraus extrahierte hoch aufgel{\"o}ste Nahkantenstruktur, XANES (engl. X-ray absorption near edge structure) qualitative Informationen {\"u}ber m{\"o}gliche Koordinations{\"a}nderungen von La, Gd und Yb in den Gl{\"a}sern liefert. Um m{\"o}gliche Unterschiede der lokalen Struktur oberhalb der Glastransformationstemperatur (TG) zur Raumtemperatur zu untersuchen, wurden exemplarisch Hochtemperatur Y-EXAFS Untersuchungen durchgef{\"u}hrt. F{\"u}r die Auswertung der EXAFS-Messungen wurde ein neu eingef{\"u}hrter Histogramm-Fit verwendet, der auch nicht-symmetrische bzw. nichtgaußf{\"o}rmige Paarverteilungsfunktionen beschreiben kann, wie sie bei einem hohen Grad der Polymerisierung bzw. bei hohen Temperaturen auftreten k{\"o}nnen. Die Y-EXAFS-Spektren f{\"u}r die Prowatke und Klemme (2005) Zusammensetzungen zeigen mit Zunahme des ASI, eine Zunahme der Asymmetrie und Breite der Y-O Paarverteilungsfunktion, welche sich in sich in der {\"A}nderung der Koordinationszahl von 6 nach 8 und einer Zunahme des Y-O Abstand um 0.13{\AA} manifestiert. Ein {\"a}hnlicher Trend l{\"a}sst sich auch f{\"u}r die Gd- und Yb-EXAFS-Spektren beobachten. Die hoch aufgel{\"o}sten XANESSpektren f{\"u}r La, Gd und Yb zeigen, dass sich die strukturellen Unterschiede zumindest halb-quantitativ bestimmen lassen. Dies gilt insbesondere f{\"u}r {\"A}nderungen im mittleren Abstand zu den Sauerstoffatomen. Im Vergleich zur EXAFS-Spektroskopie liefert XANES jedoch keine Informationen {\"u}ber die Form und Breite von Paarverteilungsfunktionen. Die Hochtemperatur EXAFS-Untersuchungen von Y zeigen {\"A}nderungen der lokalen Struktur oberhalb der Glas{\"u}bergangstemperatur an, welche sich vordergr{\"u}ndig auf eine thermisch induzierte Erh{\"o}hung des mittleren Y-O Abstandes zur{\"u}ckf{\"u}hren lassen. Allerdings zeigt ein Vergleich der Y-O Abst{\"a}nde f{\"u}r Zusammensetzungen mit einem ASI von 0.115 bzw. 0.755, ermittelt bei Raumtemperatur und TG, dass der im Glas beobachtete strukturelle Unterschied entlang der Zusammensetzungsserie in der Schmelze noch st{\"a}rker ausfallen kann, als bisher f{\"u}r die Gl{\"a}ser angenommen wurde. Die direkte Korrelation der Verteilungsdaten von Prowatke und Klemme (2005) mit den strukturellen {\"A}nderungen der Schmelzen offenbart f{\"u}r Y eine lineare Korrelation, wohingegen Yb und Gd eine nicht lineare Beziehung zeigen. Aufgrund seines Ionenradius und seiner Ladung wird das 6-fach koordinierte SEE in den niedriger polymerisierten Schmelzen bevorzugt durch nicht-br{\"u}ckenbildende Sauerstoffatome koordiniert, um stabile Konfigurationen zu bilden. In den h{\"o}her polymerisierten Schmelzen mit ASI-Werten in der N{\"a}he von 1 ist 6-fache Koordination nicht m{\"o}glich, da fast nur noch br{\"u}ckenbildende Sauerstoffatome zur Verf{\"u}gung stehen. Die {\"U}berbindung von br{\"u}ckenbildenden Sauerstoffatomen um das SEE wird durch Erh{\"o}hung der Koordinationszahl und des mittleren SEE-O Abstandes ausgeglichen. Dies bedeutet eine energetisch g{\"u}nstigere Konfiguration in den st{\"a}rker depolymerisierten Zusammensetzungen, aus welcher die beobachtete Variation des Verteilungskoeffizienten resultiert, welcher sich jedoch f{\"u}r jedes Element stark unterscheidet. F{\"u}r die haplogranitischen und haplobasaltischen Zusammensetzungen wurde mit Zunahme der Polymerisierung auch eine Zunahme der Koordinationszahl und des durchschnittlichen Bindungsabstands, einhergehend mit der Zunahme der Schiefe und der Asymmetrie der Paarverteilungsfunktion, beobachtet. Dies impliziert, dass das jeweilige SEE mit Zunahme der Polymerisierung auch inkompatibler in diesen Zusammensetzungen wird. Weiterhin zeigt die Zugabe von Wasser, dass die Schmelzen depolymerisieren, was in einer symmetrischeren Paarverteilungsfunktion resultiert, wodurch die Kompatibilit{\"a}t wieder zunimmt. Zusammenfassend zeigt sich, dass die Ver{\"a}nderungen der Schmelzzusammensetzungen in einer {\"A}nderung der Polymerisierung der Schmelzen resultieren, die dann einen signifikanten Einfluss auf die lokale Umgebung der SEE hat. Die strukturellen {\"A}nderungen lassen sich direkt mit Verteilungsdaten korrelieren, die Trends unterscheiden sich aber stark zwischen leichten, mittleren und schweren SEE. Allerdings konnte diese Studie zeigen, in welcher Gr{\"o}ßenordnung die {\"A}nderungen liegen m{\"u}ssen, um einen signifikanten Einfluss auf den Verteilungskoeffizenten zu haben. Weiterhin zeigt sich, dass der Einfluss der Schmelzzusammensetzung auf die Verteilung der Spurenelemente mit Zunahme der Polymerisierung steigt und daher nicht vernachl{\"a}ssigt werden darf.}, language = {de} } @phdthesis{Lenz2016, author = {Lenz, Josefine}, title = {Thermokarst dynamics in central-eastern Beringia}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-101364}, school = {Universit{\"a}t Potsdam}, pages = {XII, 128, A-47}, year = {2016}, abstract = {Widespread landscape changes are presently observed in the Arctic and are most likely to accelerate in the future, in particular in permafrost regions which are sensitive to climate warming. To assess current and future developments, it is crucial to understand past environmental dynamics in these landscapes. Causes and interactions of environmental variability can hardly be resolved by instrumental records covering modern time scales. However, long-term environmental variability is recorded in paleoenvironmental archives. Lake sediments are important archives that allow reconstruction of local limnogeological processes as well as past environmental changes driven directly or indirectly by climate dynamics. This study aims at reconstructing Late Quaternary permafrost and thermokarst dynamics in central-eastern Beringia, the terrestrial land mass connecting Eurasia and North America during glacial sea-level low stands. In order to investigate development, processes and influence of thermokarst dynamics, several sediment cores from extant lakes and drained lake basins were analyzed to answer the following research questions: 1. When did permafrost degradation and thermokarst lake development take place and what were enhancing and inhibiting environmental factors? 2. What are the dominant processes during thermokarst lake development and how are they reflected in proxy records? 3. How did, and still do, thermokarst dynamics contribute to the inventory and properties of organic matter in sediments and the carbon cycle? Methods applied in this study are based upon a multi-proxy approach combining sedimentological, geochemical, geochronological, and micropaleontological analyses, as well as analyses of stable isotopes and hydrochemistry of pore-water and ice. Modern field observations of water quality and basin morphometrics complete the environmental investigations. The investigated sediment cores reveal permafrost degradation and thermokarst dynamics on different time scales. The analysis of a sediment core from GG basin on the northern Seward Peninsula (Alaska) shows prevalent terrestrial accumulation of yedoma throughout the Early to Mid Wisconsin with intermediate wet conditions at around 44.5 to 41.5 ka BP. This first wetland development was terminated by the accumulation of a 1-meter-thick airfall tephra most likely originating from the South Killeak Maar eruption at 42 ka BP. A depositional hiatus between 22.5 and 0.23 ka BP may indicate thermokarst lake formation in the surrounding of the site which forms a yedoma upland till today. The thermokarst lake forming GG basin initiated 230 ± 30 cal a BP and drained in Spring 2005 AD. Four years after drainage the lake talik was still unfrozen below 268 cm depth. A permafrost core from Mama Rhonda basin on the northern Seward Peninsula preserved a full lacustrine record including several lake phases. The first lake generation developed at 11.8 cal ka BP during the Lateglacial-Early Holocene transition; its old basin (Grandma Rhonda) is still partially preserved at the southern margin of the study basin. Around 9.0 cal ka BP a shallow and more dynamic thermokarst lake developed with actively eroding shorelines and potentially intermediate shallow water or wetland phases (Mama Rhonda). Mama Rhonda lake drainage at 1.1 cal ka BP was followed by gradual accumulation of terrestrial peat and top-down refreezing of the lake talik. A significant lower organic carbon content was measured in Grandma Rhonda deposits (mean TOC of 2.5 wt\%) than in Mama Rhonda deposits (mean TOC of 7.9 wt\%) highlighting the impact of thermokarst dynamics on biogeochemical cycling in different lake generations by thawing and mobilization of organic carbon into the lake system. Proximal and distal sediment cores from Peatball Lake on the Arctic Coastal Plain of Alaska revealed young thermokarst dynamics since about 1,400 years along a depositional gradient based on reconstructions from shoreline expansion rates and absolute dating results. After its initiation as a remnant pond of a previous drained lake basin, a rapidly deepening lake with increasing oxygenation of the water column is evident from laminated sediments, and higher Fe/Ti and Fe/S ratios in the sediment. The sediment record archived characterizing shifts in depositional regimes and sediment sources from upland deposits and re-deposited sediments from drained thaw lake basins depending on the gradually changing shoreline configuration. These changes are evident from alternating organic inputs into the lake system which highlights the potential for thermokarst lakes to recycle old carbon from degrading permafrost deposits of its catchment. The lake sediment record from Herschel Island in the Yukon (Canada) covers the full Holocene period. After its initiation as a thermokarst lake at 11.7 cal ka BP and intense thermokarst activity until 10.0 cal ka BP, the steady sedimentation was interrupted by a depositional hiatus at 1.6 cal ka BP which likely resulted from lake drainage or allochthonous slumping due to collapsing shore lines. The specific setting of the lake on a push moraine composed of marine deposits is reflected in the sedimentary record. Freshening of the maturing lake is indicated by decreasing electrical conductivity in pore-water. Alternation of marine to freshwater ostracods and foraminifera confirms decreasing salinity as well but also reflects episodical re-deposition of allochthonous marine sediments. Based on permafrost and lacustrine sediment records, this thesis shows examples of the Late Quaternary evolution of typical Arctic permafrost landscapes in central-eastern Beringia and the complex interaction of local disturbance processes, regional environmental dynamics and global climate patterns. This study confirms that thermokarst lakes are important agents of organic matter recycling in complex and continuously changing landscapes.}, language = {en} } @phdthesis{Cao2014, author = {Cao, Xianyong}, title = {Vegetation and climate change in eastern continental Asia during the last 22 ka inferred from pollen data synthesis}, pages = {156}, year = {2014}, language = {en} } @phdthesis{Ramisch2015, author = {Ramisch, Arne}, title = {Lake system development on the northern Tibetan Plateau during the last ~ 12 ka}, school = {Universit{\"a}t Potsdam}, pages = {122}, year = {2015}, language = {en} } @phdthesis{Borchardt2014, author = {Borchardt, Sven}, title = {Rainfall, weathering and erosion}, pages = {x, 90}, year = {2014}, language = {en} } @phdthesis{Rach2015, author = {Rach, Oliver}, title = {Qualitative and quantitative estimations of hydrological changes in western Europe during abrupt climate shifts using lipid biomarker derived stable hydrogen isotope records}, school = {Universit{\"a}t Potsdam}, pages = {217}, year = {2015}, language = {en} } @phdthesis{Mielke2015, author = {Mielke, Christian}, title = {Multi- and Hyperspectral Spaceborne Remote Sensing for Mine Waste and Mineral Deposit Characterization, new Applications to the EnMAP and Sentinel-2 Missions}, school = {Universit{\"a}t Potsdam}, pages = {140}, year = {2015}, language = {en} } @phdthesis{Baese2016, author = {B{\"a}se, Frank}, title = {Interception loss of changing land covers in the humid tropical lowland of Latin America}, school = {Universit{\"a}t Potsdam}, pages = {ix, 85 Seiten}, year = {2016}, abstract = {Das Gebiet der feuchten Tropen ist die am st{\"a}rksten durch den Landnutzungswandel betroffene Region der Erde. Vor allem die Rodung tropischer W{\"a}lder, um Platz f{\"u}r Rinderweiden oder den Anbau von Soja zu schaffen, aber auch seit j{\"u}ngster Zeit die Bem{\"u}hungen um Wiederaufforstungen pr{\"a}gen diesen Landnutzungswandel. Dabei beeinflusst die {\"A}nderung der Vegetationsbedeckung den regionalen Wasserhaushalt auf vielf{\"a}ltige Weise. Betroffen ist unter anderem die Verdunstung von feuchten Oberfl{\"a}chen. Die so genannte Interzeptionsverdunstung bzw. der Interzeptionsverlust tr{\"a}gt erheblich zum Wasserdampfgehalt in der unteren Atmosph{\"a}re und schließlich zur Niederschlagsbildung bei. Ziele dieser Dissertation waren (1) die experimentelle Untersuchung der Interzeptionsverlustunterschiede zwischen einem nat{\"u}rlichen, tropischen Wald und einer Sojaplantage im s{\"u}dlichen Amazonasgebiet, (2) die Modellierung des Interzeptionsverlustes dieser beiden Vegetationsformen im Vergleich zu einem jungen Sekund{\"a}rwald unter dem Aspekt der Unsicherheiten bei der Ableitung notwendiger Modellparameter sowohl im S{\"u}damazonas als auch im Einzugsgebietes des Panamakanals sowie (3) die Wasserhaushaltsanalyse eines vom Landnutzungswandel gepr{\"a}gten Teileinzugsgebietes des Panamakanals in Hinblick auf die Ver{\"a}nderung der Interzeptionsverdunstung durch sich ver{\"a}ndernde Landnutzung und der {\"A}nderung der klimatischen Bedingungen. Die Messung des Interzeptionsverlustes zeigte, dass in der Hauptwachstumsphase vom Soja von dessen Oberfl{\"a}che mehr Wasserverdunstet als von der Oberfl{\"a}che des Waldes. Allerdings ist in der Jahresbilanz der Interzeptionsverlust vom Wald h{\"o}her, da diese Studie nur eine Momentaufnahme zur Zeit der vollen Vegetationsentwicklung des Sojas mit einem Zeitfenster von zwei Monaten widerspiegelt. Durch die geringere ganzj{\"a}hrige Verdunstung von den mit Soja bestandenen Fl{\"a}chen, wird hier der Niederschlag schneller dem Abfluss zugef{\"u}hrt und schell aus der Region ausgetragen. Somit tr{\"a}gt der Landnutzungswandel von Wald zu Soja zu einer mittelfristigen Reduktion des in der Region verf{\"u}gbaren Wassers bei. Die anschließende Modellierung des Interzeptionsverlustes zeigte Einerseits einen starken Einfluss der Datenqualit{\"a}t auf die Plausibilit{\"a}t der Ergebnisse und Andererseits, dass die Sensitivit{\"a}t der einzelnen Parameter zwischen den Untersuchungsgebieten variiert. Eine Schl{\"u}sselrolle nimmt die Wasserspeicherkapazit{\"a}t der Vegetationskrone ein. Dennoch ist die Evaporationsrate die treibende Gr{\"o}ße im Interzeptionsprozess, so dass von ihr die gr{\"o}ßte Unsicherheit ausgeht. Je nach verwendeter Methode zur Ableitung dieses Parameters unterscheiden sich die gewonnenen Parameterwerte erheblich. Die Wirkungsanalyse der Interzeptionsverdunstung auf den Wasserhaushalt im Wirkungsgeflecht der {\"A}nderungen von Temperatur, Niederschlag und Landnutzung im Landschaftsmosaik eines Flusseinzugsgebiets mit Hilfe eines Wasserhaushaltsmodels zeigte den Einfluss der Landnutzungs{\"a}nderung auf die Abflussbildung mittels verschiedener Landnutzungsszenarien. Die Ergebnisse belegen, dass die Landnutzungs{\"a}nderung im Gebiet nur einen geringen Einfluss auf den Jahresabfluss hat. St{\"a}rker scheint sich der gemessene Temperaturanstieg auf die Verdunstung auszuwirken. Der mit einer h{\"o}heren Temperatur einhergehende Anstieg der Transpiration und Interzeptionsverdunstung gleicht die gemessene Zunahme des Gebietsniederschlages aus, sodass keine signifikanten {\"A}nderungen im Jahresabfluss nachgewiesen werden konnten. Die Ergebnisse der drei Studien verdeutlichen den Einfluss der Landnutzung auf die Interzeptionsverdunstung. Allerdings veranschaulichten die Resultate der Wasserhaushalts-modellierung, wie sehr dieser Einfluss durch die Ver{\"a}nderung der {\"a}ußeren Rahmenbedingungen, vor allem durch den Anstieg der Temperatur, {\"u}berpr{\"a}gt werden kann. Dies belegt, dass eine einfache {\"U}bertragung der Ergebnisse zwischen den Untersuchungsgebiet nicht m{\"o}glich ist. Somit bleibt die experimentelle Erhebung von Vegetationsparametern sowie des Interzeptionsverlustes an den jeweils zu untersuchenden Standort f{\"u}r die Anwendung von Modellen unerl{\"a}sslich.}, language = {en} } @phdthesis{Draeger2016, author = {Dr{\"a}ger, Nadine}, title = {Holocene climate and environmental variability in NE Germany inferred from annually laminated lake sediments}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-103037}, school = {Universit{\"a}t Potsdam}, pages = {xv, 144 Seiten}, year = {2016}, abstract = {Understanding the role of natural climate variability under the pressure of human induced changes of climate and landscapes, is crucial to improve future projections and adaption strategies. This doctoral thesis aims to reconstruct Holocene climate and environmental changes in NE Germany based on annually laminated lake sediments. The work contributes to the ICLEA project (Integrated CLimate and Landscape Evolution Analyses). ICLEA intends to compare multiple high-resolution proxy records with independent chronologies from the N central European lowlands, in order to disentangle the impact of climate change and human land use on landscape development during the Lateglacial and Holocene. In this respect, two study sites in NE Germany are investigated in this doctoral project, Lake Tiefer See and palaeolake Wukenfurche. While both sediment records are studied with a combination of high-resolution sediment microfacies and geochemical analyses (e.g. µ-XRF, carbon geochemistry and stable isotopes), detailed proxy understanding mainly focused on the continuous 7.7 m long sediment core from Lake Tiefer See covering the last ~6000 years. Three main objectives are pursued at Lake Tiefer See: (1) to perform a reliable and independent chronology, (2) to establish microfacies and geochemical proxies as indicators for climate and environmental changes, and (3) to trace the effects of climate variability and human activity on sediment deposition. Addressing the first aim, a reliable chronology of Lake Tiefer See is compiled by using a multiple-dating concept. Varve counting and tephra findings form the chronological framework for the last ~6000 years. The good agreement with independent radiocarbon dates of terrestrial plant remains verifies the robustness of the age model. The resulting reliable and independent chronology of Lake Tiefer See and, additionally, the identification of nine tephras provide a valuable base for detailed comparison and synchronization of the Lake Tiefer See data set with other climate records. The sediment profile of Lake Tiefer See exhibits striking alternations between well-varved and non-varved sediment intervals. The combination of microfacies, geochemical and microfossil (i.e. Cladocera and diatom) analyses indicates that these changes of varve preservation are caused by variations of lake circulation in Lake Tiefer See. An exception is the well-varved sediment deposited since AD 1924, which is mainly influenced by human-induced lake eutrophication. Well-varved intervals before the 20th century are considered to reflect phases of reduced lake circulation and, consequently, stronger anoxic conditions. Instead, non-varved intervals indicate increased lake circulation in Lake Tiefer See, leading to more oxygenated conditions at the lake ground. Furthermore, lake circulation is not only influencing sediment deposition, but also geochemical processes in the lake. As, for example, the proxy meaning of δ13COM varies in time in response to changes of the oxygen regime in the lake hypolinion. During reduced lake circulation and stronger anoxic conditions δ13COM is influenced by microbial carbon cycling. In contrast, organic matter degradation controls δ13COM during phases of intensified lake circulation and more oxygenated conditions. The varve preservation indicates an increasing trend of lake circulation at Lake Tiefer See after ~4000 cal a BP. This trend is superimposed by decadal to centennial scale variability of lake circulation intensity. Comparison to other records in Central Europe suggests that the long-term trend is probably related to gradual changes in Northern Hemisphere orbital forcing, which induced colder and windier conditions in Central Europe and, therefore, reinforced lake circulation. Decadal to centennial scale periods of increased lake circulation coincide with settlement phases at Lake Tiefer See, as inferred from pollen data of the same sediment record. Deforestation reduced the wind shelter of the lake, which probably increased the sensitivity of lake circulation to wind stress. However, results of this thesis also suggest that several of these phases of increased lake circulation are additionally reinforced by climate changes. A first indication is provided by the comparison to the Baltic Sea record, which shows striking correspondence between major non-varved intervals at Lake Tiefer See and bioturbated sediments in the Baltic Sea. Furthermore, a preliminary comparison to the ICLEA study site Lake Czechowskie (N central Poland) shows a coincidence of at least three phases of increased lake circulation in both lakes, which concur with periods of known climate changes (2.8 ka event, 'Migration Period' and 'Little Ice Age'). These results suggest an additional over-regional climate forcing also on short term increased of lake circulation in Lake Tiefer See. In summary, the results of this thesis suggest that lake circulation at Lake Tiefer See is driven by a combination of long-term and short-term climate changes as well as of anthropogenic deforestation phases. Furthermore, the lake circulation drives geochemical cycles in the lake affecting the meaning of proxy data. Therefore, the work presented here expands the knowledge of climate and environmental variability in NE Germany. Furthermore, the integration of the Lake Tiefer See multi-proxy record in a regional comparison with another ICLEA side, Lake Czechowskie, enabled to better decipher climate changes and human impact on the lake system. These first results suggest a huge potential for further detailed regional comparisons to better understand palaeoclimate dynamics in N central Europe.}, language = {en} } @phdthesis{Luft2015, author = {Luft, Laura Charlotte}, title = {Bridging the gap between science and nature conservation practice}, school = {Universit{\"a}t Potsdam}, pages = {173}, year = {2015}, language = {en} } @article{HaugSigman2009, author = {Haug, Gerald H. and Sigman, Daniel M.}, title = {Palaeoceanography : polar twins}, issn = {1752-0894}, doi = {10.1038/Ngeo423}, year = {2009}, abstract = {Ice ages in the North Pacific Ocean and the Southern Ocean were marked by low productivity. Accumulating evidence indicates that strong stratification restricted the supply of nutrients from the deep ocean to the algae of the sunlit surface in these regions.}, language = {en} } @article{HippeKoberZeilingeretal.2009, author = {Hippe, Kristina and Kober, Florian and Zeilinger, Gerald and Ivy-Ochs, Susan and Kubik, Peter W. and Wieler, Rainer}, title = {Short and long-term denudation rates at the Altiplano margin, La Paz region, Bolivia}, issn = {0016-7037}, doi = {10.1016/j.gca.2009.05.006}, year = {2009}, language = {en} } @phdthesis{Stagl2016, author = {Stagl, Judith C.}, title = {Ecosystems' exposure to climate change - Modeling as support for nature conservation management}, school = {Universit{\"a}t Potsdam}, pages = {127}, year = {2016}, language = {en} } @phdthesis{Emberson2016, author = {Emberson, Robert}, title = {Chemical weathering driven by bedrock landslides}, school = {Universit{\"a}t Potsdam}, pages = {221}, year = {2016}, language = {en} } @article{TuominenEerikaeinenSchibalskietal.2010, author = {Tuominen, Sakari and Eerik{\"a}inen, Kalle and Schibalski, Anett and Haakana, Markus and Lehtonen, Aleksi}, title = {Mapping Biomass Variables with a Multi-Source Forest Inventory Technique}, issn = {0037-5330}, year = {2010}, abstract = {Map form information on forest biomass is required for estimating bioenergy potentials and monitoring carbon stocks. In Finland, the growing stock of forests is monitored using multi-source forest inventory, where variables are estimated in the form of thematic maps and area statistics by combining information of field measurements, satellite images and other digital map data. In this study, we used the multi-source forest inventory methodology for estimating forest biomass characteristics. The biomass variables were estimated for national forest inventory field plots on the basis of measured tree variables. The plot-level biomass estimates were used as reference data for satellite image interpretation. The estimates produced by satellite image interpretation were tested by cross-validation. The results indicate that the method for producing biomass maps on the basis of biomass models and satellite image interpretation is operationally feasible. Furthermore, the accuracy of the estimates of biomass variables is similar or even higher than that of traditional growing stock volume estimates. The technique presented here can be applied, for example, in estimating biomass resources or in the inventory of greenhouse gases.}, language = {en} } @article{ZimmermannZimmermannLarketal.2010, author = {Zimmermann, Beate and Zimmermann, Alexander and Lark, Richard M. and Elsenbeer, Helmut}, title = {Sampling procedures for throughfall monitoring : a simulation study}, issn = {0043-1397}, doi = {10.1029/2009wr007776}, year = {2010}, abstract = {What is the most appropriate sampling scheme to estimate event-based average throughfall? A satisfactory answer to this seemingly simple question has yet to be found, a failure which we attribute to previous efforts' dependence on empirical studies. Here we try to answer this question by simulating stochastic throughfall fields based on parameters for statistical models of large monitoring data sets. We subsequently sampled these fields with different sampling designs and variable sample supports. We evaluated the performance of a particular sampling scheme with respect to the uncertainty of possible estimated means of throughfall volumes. Even for a relative error limit of 20\%, an impractically large number of small, funnel-type collectors would be required to estimate mean throughfall, particularly for small events. While stratification of the target area is not superior to simple random sampling, cluster random sampling involves the risk of being less efficient. A larger sample support, e.g., the use of trough-type collectors, considerably reduces the necessary sample sizes and eliminates the sensitivity of the mean to outliers. Since the gain in time associated with the manual handling of troughs versus funnels depends on the local precipitation regime, the employment of automatically recording clusters of long troughs emerges as the most promising sampling scheme. Even so, a relative error of less than 5\% appears out of reach for throughfall under heterogeneous canopies. We therefore suspect a considerable uncertainty of input parameters for interception models derived from measured throughfall, in particular, for those requiring data of small throughfall events.}, language = {en} } @misc{HiemerRoesslerScherbaum2010, author = {Hiemer, Stefan and R{\"o}ßler, Dirk and Scherbaum, Frank}, title = {Catalog of Swarm Earthquakes in Vogtland /West Bohemia in 2008/09}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-51710}, year = {2010}, abstract = {The document contains the catalog of earthquakes in Vogtland /West Bohemia within the period of 2008/10/19 -to- 2009/03/16. The events were recorded by a seismic mini-array operated by the Institute of Earthsciences, University of Postdam.}, language = {en} } @phdthesis{Shirzaei2010, author = {Shirzaei, Manoochehr}, title = {Crustal deformation source monitoring using advanced InSAR time series and time dependent inverse modeling}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-50774}, school = {Universit{\"a}t Potsdam}, year = {2010}, abstract = {Crustal deformation can be the result of volcanic and tectonic activity such as fault dislocation and magma intrusion. The crustal deformation may precede and/or succeed the earthquake occurrence and eruption. Mitigating the associated hazard, continuous monitoring of the crustal deformation accordingly has become an important task for geo-observatories and fast response systems. Due to highly non-linear behavior of the crustal deformation fields in time and space, which are not always measurable using conventional geodetic methods (e.g., Leveling), innovative techniques of monitoring and analysis are required. In this thesis I describe novel methods to improve the ability for precise and accurate mapping the spatiotemporal surface deformation field using multi acquisitions of satellite radar data. Furthermore, to better understand the source of such spatiotemporal deformation fields, I present novel static and time dependent model inversion approaches. Almost any interferograms include areas where the signal decorrelates and is distorted by atmospheric delay. In this thesis I detail new analysis methods to reduce the limitations of conventional InSAR, by combining the benefits of advanced InSAR methods such as the permanent scatterer InSAR (PSI) and the small baseline subsets (SBAS) with a wavelet based data filtering scheme. This novel InSAR time series methodology is applied, for instance, to monitor the non-linear deformation processes at Hawaii Island. The radar phase change at Hawaii is found to be due to intrusions, eruptions, earthquakes and flank movement processes and superimposed by significant environmental artifacts (e.g., atmospheric). The deformation field, I obtained using the new InSAR analysis method, is in good agreement with continuous GPS data. This provides an accurate spatiotemporal deformation field at Hawaii, which allows time dependent source modeling. Conventional source modeling methods usually deal with static deformation field, while retrieving the dynamics of the source requires more sophisticated time dependent optimization approaches. This problem I address by combining Monte Carlo based optimization approaches with a Kalman Filter, which provides the model parameters of the deformation source consistent in time. I found there are numerous deformation sources at Hawaii Island which are spatiotemporally interacting, such as volcano inflation is associated to changes in the rifting behavior, and temporally linked to silent earthquakes. I applied these new methods to other tectonic and volcanic terrains, most of which revealing the importance of associated or coupled deformation sources. The findings are 1) the relation between deep and shallow hydrothermal and magmatic sources underneath the Campi Flegrei volcano, 2) gravity-driven deformation at Damavand volcano, 3) fault interaction associated with the 2010 Haiti earthquake, 4) independent block wise flank motion at the Hilina Fault system, Kilauea, and 5) interaction between salt diapir and the 2005 Qeshm earthquake in southern Iran. This thesis, written in cumulative form including 9 manuscripts published or under review in peer reviewed journals, improves the techniques for InSAR time series analysis and source modeling and shows the mutual dependence between adjacent deformation sources. These findings allow more realistic estimation of the hazard associated with complex volcanic and tectonic systems.}, language = {en} } @phdthesis{Wichura2011, author = {Wichura, Henry}, title = {Topographic evolution of the East African Plateau : a combined study on lava-flow modeling and paleo-topography}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52363}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {The East African Plateau provides a spectacular example of geodynamic plateau uplift, active continental rifting, and associated climatic forcing. It is an integral part of the East African Rift System and has an average elevation of approximately 1,000 m. Its location coincides with a negative Bouguer gravity anomaly with a semi-circular shape, closely related to a mantle plume, which influences the Cenozoic crustal development since its impingement in Eocene-Oligocene time. The uplift of the East African Plateau, preceding volcanism, and rifting formed an important orographic barrier and tectonically controlled environment, which is profoundly influenced by climate driven processes. Its location within the equatorial realm supports recently proposed hypotheses, that topographic changes in this region must be considered as the dominant forcing factor influencing atmospheric circulation patterns and rainfall distribution. The uplift of this region has therefore often been associated with fundamental climatic and environmental changes in East Africa and adjacent regions. While the far-reaching influence of the plateau uplift is widely accepted, the timing and the magnitude of the uplift are ambiguous and are still subject to ongoing discussion. This dilemma stems from the lack of datable, geomorphically meaningful reference horizons that could record surface uplift. In order to quantify the amount of plateau uplift and to find evidence for the existence of significant relief along the East African Plateau prior to rifting, I analyzed and modeled one of the longest terrestrial lava flows; the 300-km-long Yatta phonolite flow in Kenya. This lava flow is 13.5 Ma old and originated in the region that now corresponds to the eastern rift shoulders. The phonolitic flow utilized an old riverbed that once drained the eastern flank of the plateau. Due to differential erosion this lava flow now forms a positive relief above the parallel-flowing Athi River, which is mimicking the course of the paleo-river. My approach is a lava-flow modeling, based on an improved composition and temperature dependent method to parameterize the flow of an arbitrary lava in a rectangular-shaped channel. The essential growth pattern is described by a one-dimensional model, in which Newtonian rheological flow advance is governed by the development of viscosity and/or velocity in the internal parts of the lava-flow front. Comparing assessments of different magma compositions reveal that length-dominated, channelized lava flows are characterized by high effusion rates, rapid emplacement under approximately isothermal conditions, and laminar flow. By integrating the Yatta lava flow dimensions and the covered paleo-topography (slope angle) into the model, I was able to determine the pre-rift topography of the East African Plateau. The modeling results yield a pre-rift slope of at least 0.2°, suggesting that the lava flow must have originated at a minimum elevation of 1,400 m. Hence, high topography in the region of the present-day Kenya Rift must have existed by at least 13.5 Ma. This inferred mid-Miocene uplift coincides with the two-step expansion of grasslands, as well as important radiation and speciation events in tropical Africa. Accordingly, the combination of my results regarding the Yatta lava flow emplacement history, its location, and its morphologic character, validates it as a suitable "paleo-tiltmeter" and has thus to be considered as an important topographic and volcanic feature for the topographic evolution in East Africa.}, language = {en} } @phdthesis{Radeff2014, author = {Radeff, Giuditta}, title = {Geohistory of the Central Anatolian Plateau southern margin (southern Turkey)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-71865}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {The Adana Basin of southern Turkey, situated at the SE margin of the Central Anatolian Plateau is ideally located to record Neogene topographic and tectonic changes in the easternmost Mediterranean realm. Using industry seismic reflection data we correlate 34 seismic profiles with corresponding exposed units in the Adana Basin. The time-depth conversion of the interpreted seismic profiles allows us to reconstruct the subsidence curve of the Adana Basin and to outline the occurrence of a major increase in both subsidence and sedimentation rates at 5.45 - 5.33 Ma, leading to the deposition of almost 1500 km3 of conglomerates and marls. Our provenance analysis of the conglomerates reveals that most of the sediment is derived from and north of the SE margin of the Central Anatolian Plateau. A comparison of these results with the composition of recent conglomerates and the present drainage basins indicates major changes between late Messinian and present-day source areas. We suggest that these changes in source areas result of uplift and ensuing erosion of the SE margin of the plateau. This hypothesis is supported by the comparison of the Adana Basin subsidence curve with the subsidence curve of the Mut Basin, a mainly Neogene basin located on top of the Central Anatolian Plateau southern margin, showing that the Adana Basin subsidence event is coeval with an uplift episode of the plateau southern margin. The collection of several fault measurements in the Adana region show different deformation styles for the NW and SE margins of the Adana Basin. The weakly seismic NW portion of the basin is characterized by extensional and transtensional structures cutting Neogene deposits, likely accomodating the differential uplift occurring between the basin and the SE margin of the plateau. We interpret the tectonic evolution of the southern flank of the Central Anatolian Plateau and the coeval subsidence and sedimentation in the Adana Basin to be related to deep lithospheric processes, particularly lithospheric delamination and slab break-off.}, language = {en} } @phdthesis{Bischoff2013, author = {Bischoff, Juliane}, title = {Microbial communities and their response to Pleistocene and Holocene climate variabilities in the Russian Arctic}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68895}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The Arctic is considered as a focal region in the ongoing climate change debate. The currently observed and predicted climate warming is particularly pronounced in the high northern latitudes. Rising temperatures in the Arctic cause progressive deepening and duration of permafrost thawing during the arctic summer, creating an 'active layer' with high bioavailability of nutrients and labile carbon for microbial consumption. The microbial mineralization of permafrost carbon creates large amounts of greenhouse gases, including carbon dioxide and methane, which can be released to the atmosphere, creating a positive feedback to global warming. However, to date, the microbial communities that drive the overall carbon cycle and specifically methane production in the Arctic are poorly constrained. To assess how these microbial communities will respond to the predicted climate changes, such as an increase in atmospheric and soil temperatures causing increased bioavailability of organic carbon, it is necessary to investigate the current status of this environment, but also how these microbial communities reacted to climate changes in the past. This PhD thesis investigated three records from two different study sites in the Russian Arctic, including permafrost, lake shore and lake deposits from Siberia and Chukotka. A combined stratigraphic approach of microbial and molecular organic geochemical techniques were used to identify and quantify characteristic microbial gene and lipid biomarkers. Based on this data it was possible to characterize and identify the climate response of microbial communities involved in past carbon cycling during the Middle Pleistocene and the Late Pleistocene to Holocene. It is shown that previous warmer periods were associated with an expansion of bacterial and archaeal communities throughout the Russian Arctic, similar to present day conditions. Different from this situation, past glacial and stadial periods experienced a substantial decrease in the abundance of Bacteria and Archaea. This trend can also be confirmed for the community of methanogenic archaea that were highly abundant and diverse during warm and particularly wet conditions. For the terrestrial permafrost, a direct effect of the temperature on the microbial communities is likely. In contrast, it is suggested that the temperature rise in scope of the glacial-interglacial climate variations led to an increase of the primary production in the Arctic lake setting, as can be seen in the corresponding biogenic silica distribution. The availability of this algae-derived carbon is suggested to be a driver for the observed pattern in the microbial abundance. This work demonstrates the effect of climate changes on the community composition of methanogenic archae. Methanosarcina-related species were abundant throughout the Russian Arctic and were able to adapt to changing environmental conditions. In contrast, members of Methanocellales and Methanomicrobiales were not able to adapt to past climate changes. This PhD thesis provides first evidence that past climatic warming led to an increased abundance of microbial communities in the Arctic, closely linked to the cycling of carbon and methane production. With the predicted climate warming, it may, therefore, be anticipated that extensive amounts of microbial communities will develop. Increasing temperatures in the Arctic will affect the temperature sensitive parts of the current microbiological communities, possibly leading to a suppression of cold adapted species and the prevalence of methanogenic archaea that tolerate or adapt to increasing temperatures. These changes in the composition of methanogenic archaea will likely increase the methane production potential of high latitude terrestrial regions, changing the Arctic from a carbon sink to a source.}, language = {en} } @phdthesis{BaumannWilke2013, author = {Baumann-Wilke, Maria}, title = {Combining body wave tomography, surface wave inversion, seismic interferometry and laboratory measurements to characterize the black shales on Bornholm at different scales}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69007}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Black shales are sedimentary rocks with a high content of organic carbon, which leads to a dark grayish to black color. Due to their potential to contain oil or gas, black shales are of great interest for the support of the worldwide energy supply. An integrated seismic investigation of the Lower Palaeozoic black shales was carried out at the Danish island Bornholm to locate the shallow-lying Alum Shale layer and its surrounding formations and to characterize its potential as a source rock. Therefore, two seismic experiments at a total of three crossing profiles were carried out in October 2010 and in June 2012 in the southern part of the island. Two different active measurements were conducted with either a weight drop source or a minivibrator. Additionally, the ambient noise field was recorded at the study location over a time interval of about one day, and also a laboratory analysis of borehole samples was carried out. The seismic profiles were positioned as close as possible to two scientific boreholes which were used for comparative purposes. The seismic field data was analyzed with traveltime tomography, surface wave inversion and seismic interferometry to obtain the P-wave and S-wave velocity models of the subsurface. The P-wave velocity models which were determined for all three profiles clearly locate the Alum Shale layer between the Komstad Limestone layer on top and the L{\ae}s{\aa} Sandstone Formation at the base of the models. The black shale layer has P-wave velocities around 3 km/s which are lower compared to the adjacent formations. Due to a very good agreement of the sonic log and the vertical velocity profiles of the two seismic lines, which are directly crossing the borehole where the sonic log was conducted, the reliability of the traveltime tomography is proven. A correlation of the seismic velocities with the content of organic carbon is an important task for the characterization of the reservoir properties of a black shale formation. It is not possible without calibration but in combination with a full 2D tomographic image of the subsurface it gives the subsurface distribution of the organic material. The S-wave model obtained with surface wave inversion of the vibroseis data of one of the profiles images the Alum Shale layer also very well with S-wave velocities around 2 km/s. Although individual 1D velocity models for each of the source positions were determined, the subsurface S-wave velocity distribution is very uniform with a good match between the single models. A really new approach described here is the application of seismic interferometry to a really small study area and a quite short time interval. Also new is the selective procedure of only using time windows with the best crosscorrelation signals to achieve the final interferograms. Due to the small scale of the interferometry even P-wave signals can be observed in the final crosscorrelations. In the laboratory measurements the seismic body waves were recorded for different pressure and temperature stages. Therefore, samples of different depths of the Alum Shale were available from one of the scientific boreholes at the study location. The measured velocities have a high variance with changing pressure or temperature. Recordings with wave propagation both parallel and perpendicular to the bedding of the samples reveal a great amount of anisotropy for the P-wave velocity, whereas the S-wave velocity is almost independent of the wave direction. The calculated velocity ratio is also highly anisotropic with very low values for the perpendicular samples and very high values for the parallel ones. Interestingly, the laboratory velocities of the perpendicular samples are comparable to the velocities of the field experiments indicating that the field measurements are sensitive to wave propagation in vertical direction. The velocity ratio is also calculated with the P-wave and S-wave velocity models of the field experiments. Again, the Alum Shale can be clearly separated from the adjacent formations because it shows overall very low vP/vS ratios around 1.4. The very low velocity ratio indicates the content of gas in the black shale formation. With the combination of all the different methods described here, a comprehensive interpretation of the seismic response of the black shale layer can be made and the hydrocarbon source rock potential can be estimated.}, language = {en} } @phdthesis{Thomas2013, author = {Thomas, Bj{\"o}rn Daniel}, title = {Analysis and management of low flows in small catchments of Brandenburg, Germany}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69247}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Water management and environmental protection is vulnerable to extreme low flows during streamflow droughts. During the last decades, in most rivers of Central Europe summer runoff and low flows have decreased. Discharge projections agree that future decrease in runoff is likely for catchments in Brandenburg, Germany. Depending on the first-order controls on low flows, different adaption measures are expected to be appropriate. Small catchments were analyzed because they are expected to be more vulnerable to a changing climate than larger rivers. They are mainly headwater catchments with smaller ground water storage. Local characteristics are more important at this scale and can increase vulnerability. This thesis mutually evaluates potential adaption measures to sustain minimum runoff in small catchments of Brandenburg, Germany, and similarities of these catchments regarding low flows. The following guiding questions are addressed: (i) Which first-order controls on low flows and related time scales exist? (ii) Which are the differences between small catchments regarding low flow vulnerability? (iii) Which adaption measures to sustain minimum runoff in small catchments of Brandenburg are appropriate considering regional low flow patterns? Potential adaption measures to sustain minimum runoff during periods of low flows can be classified into three categories: (i) increase of groundwater recharge and subsequent baseflow by land use change, land management and artificial ground water recharge, (ii) increase of water storage with regulated outflow by reservoirs, lakes and wetland water management and (iii) regional low flow patterns have to be considered during planning of measures with multiple purposes (urban water management, waste water recycling and inter-basin water transfer). The question remained whether water management of areas with shallow groundwater tables can efficiently sustain minimum runoff. Exemplary, water management scenarios of a ditch irrigated area were evaluated using the model Hydrus-2D. Increasing antecedent water levels and stopping ditch irrigation during periods of low flows increased fluxes from the pasture to the stream, but storage was depleted faster during the summer months due to higher evapotranspiration. Fluxes from this approx. 1 km long pasture with an area of approx. 13 ha ranged from 0.3 to 0.7 l\s depending on scenario. This demonstrates that numerous of such small decentralized measures are necessary to sustain minimum runoff in meso-scale catchments. Differences in the low flow risk of catchments and meteorological low flow predictors were analyzed. A principal component analysis was applied on daily discharge of 37 catchments between 1991 and 2006. Flows decreased more in Southeast Brandenburg according to meteorological forcing. Low flow risk was highest in a region east of Berlin because of intersection of a more continental climate and the specific geohydrology. In these catchments, flows decreased faster during summer and the low flow period was prolonged. A non-linear support vector machine regression was applied to iteratively select meteorological predictors for annual 30-day minimum runoff in 16 catchments between 1965 and 2006. The potential evapotranspiration sum of the previous 48 months was the most important predictor (r²=0.28). The potential evapotranspiration of the previous 3 months and the precipitation of the previous 3 months and last year increased model performance (r²=0.49, including all four predictors). Model performance was higher for catchments with low yield and more damped runoff. In catchments with high low flow risk, explanatory power of long term potential evapotranspiration was high. Catchments with a high low flow risk as well as catchments with a considerable decrease in flows in southeast Brandenburg have the highest demand for adaption. Measures increasing groundwater recharge are to be preferred. Catchments with high low flow risk showed relatively deep and decreasing groundwater heads allowing increased groundwater recharge at recharge areas with higher altitude away from the streams. Low flows are expected to stay low or decrease even further because long term potential evapotranspiration was the most important low flow predictor and is projected to increase during climate change. Differences in low flow risk and runoff dynamics between catchments have to be considered for management and planning of measures which do not only have the task to sustain minimum runoff.}, language = {en} } @phdthesis{Abdelfadil2013, author = {Abdelfadil, Khaled Mohamed}, title = {Geochemistry of Variscan lamprophyre magmatism in the Saxo-Thuringian Zone}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68854}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Lamprophyres are mantle-derived magmatic rocks, commonly occurring as dikes. They are readily identified from their field setting, petrography, chemical and mineralogical composition. These rocks not only provide important information on melting processes in the mantle, but also on geodynamic processes modifying the mantle. There are numerous occurrences of lamprophyres in the Saxo-Thuringian Zone of Variscan Central Europe, which are useful to track the variable effects of the Variscan orogeny on local mantle evolution. This work presents and evaluates the mineralogical, geochemical, and Sr-Nd-Pb isotopic data of late-Variscan calc-alkaline lamprophyres, post-Variscan ultramafic lamprophyres, of alkaline basalt from Lusatia, and, for comparison, of pre-Variscan gabbros. In addition, lithium isotopic signatures combined with Sr-Nd-Pb isotopic data of late-Variscan calc-alkaline lamprophyres from three different Variscan Domains (i.e., Erzgebirge, Lusatia, and Sudetes) are used to assess compositional changes of the mantle during Variscan orogeny.}, language = {de} } @phdthesis{Polanski2011, author = {Polanski, Stefan}, title = {Simulation der indischen Monsunzirkulation mit dem Regionalen Klimamodell HIRHAM}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52508}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {In dieser Arbeit wird das regionale Klimamodell HIRHAM mit einer horizontalen Aufl{\"o}sung von 50 km und 19 vertikalen Schichten erstmals auf den asiatischen Kontinent angewendet, um die indische Monsunzirkulation unter rezenten und pal{\"a}oklimatischen Bedingungen zu simulieren. Das Integrationsgebiet des Modells erstreckt sich von etwa 0ºN - 50ºN und 42ºE - 110ºE und bedeckt dabei sowohl die hohe Topographie des Himalajas und Tibet Plateaus als auch den n{\"o}rdlichen Indischen Ozean. Das Ziel besteht in der Beschreibung der regionalen Kopplung zwischen der Monsunzirkulation und den orographischen sowie diabatischen Antriebsmechanismen. Eine 44-j{\"a}hrige Modellsimulation von 1958-2001, die am seitlichen und unteren Rand von ECMWF Reanalysen (ERA40) angetrieben wird, bildet die Grundlage f{\"u}r die Validierung der Modellergebnisse mit Beobachtungen auf der Basis von Stations- und Gitterdatens{\"a}tzen. Der Fokus liegt dabei auf der atmosph{\"a}rischen Zirkulation, der Temperatur und dem Niederschlag im Sommer- und Wintermonsun, wobei die Qualit{\"a}t des Modells sowohl in Bezug zur langfristigen und dekadischen Klimatologie als auch zur interannuellen Variabilit{\"a}t evaluiert wird. Im Zusammenhang mit einer realistischen Reproduktion der Modelltopographie kann f{\"u}r die Muster der Zirkulation und Temperatur eine gute {\"U}bereinstimmung zwischen Modell und Daten nachgewiesen werden. Der simulierte Niederschlag zeigt eine bessere {\"U}bereinstimmung mit einem hoch aufgel{\"o}sten Gitterdatensatz {\"u}ber der Landoberfl{\"a}che Zentralindiens und in den Hochgebirgsregionen, der den Vorteil des Regionalmodells gegen{\"u}ber der antreibenden Reanalyse hervorhebt. In verschiedenen Fall- und Sensitivit{\"a}tsstudien werden die wesentlichen Antriebsfaktoren des indischen Monsuns (Meeresoberfl{\"a}chentemperaturen, St{\"a}rke des winterlichen Sibirischen Hochs und Anomalien der Bodenfeuchte) untersucht. Die Ergebnisse machen deutlich, dass die Simulation dieser Mechanismen auch mit einem Regionalmodell sehr schwierig ist, da die Komplexit{\"a}t des Monsunsystems hochgradig nichtlinear ist und die vor allem subgridskalig wirkenden Prozesse im Modell noch nicht ausreichend parametrisiert und verstanden sind. Ein pal{\"a}oklimatisches Experiment f{\"u}r eine 44-j{\"a}hrige Zeitscheibe im mittleren Holoz{\"a}n (etwa 6000 Jahre vor heute), die am Rand von einer globalen ECHAM5 Simulation angetrieben wird, zeigt markante Ver{\"a}nderungen in der Intensit{\"a}t des Monsuns durch die unterschiedliche solare Einstrahlung, die wiederum Einfl{\"u}sse auf die SST, die Zirkulation und damit auf die Niederschlagsmuster hat.}, language = {de} } @phdthesis{Wischnewski2011, author = {Wischnewski, Juliane}, title = {Reconstructing climate variability on the Tibetan Plateau : comparing aquatic and terrestrial signals}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52453}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {Spatial and temporal temperature and moisture patterns across the Tibetan Plateau are very complex. The onset and magnitude of the Holocene climate optimum in the Asian monsoon realm, in particular, is a subject of considerable debate as this time period is often used as an analogue for recent global warming. In the light of contradictory inferences regarding past climate and environmental change on the Tibetan Plateau, I have attempted to explain mismatches in the timing and magnitude of change. Therefore, I analysed the temporal variation of fossil pollen and diatom spectra and the geochemical record from palaeo-ecological records covering different time scales (late Quaternary and the last 200 years) from two core regions in the NE and SE Tibetan Plateau. For interpretation purposes I combined my data with other available palaeo-ecological data to set up corresponding aquatic and terrestrial proxy data sets of two lake pairs and two sets of sites. I focused on the direct comparison of proxies representing lacustrine response to climate signals (e.g., diatoms, ostracods, geochemical record) and proxies representing changes in the terrestrial environment (i.e., terrestrial pollen), in order to asses whether the lake and its catchments respond at similar times and magnitudes to environmental changes. Therefore, I introduced the established numerical technique procrustes rotation as a new approach in palaeoecology to quantitatively compare raw data of any two sedimentary records of interest in order to assess their degree of concordance. Focusing on the late Quaternary, sediment cores from two lakes (Kuhai Lake 35.3°N; 99.2°E; 4150 m asl; and Koucha Lake 34.0°N; 97.2°E; 4540 m asl) on the semi-arid northeastern Tibetan Plateau were analysed to identify post-glacial vegetation and environmental changes, and to investigate the responses of lake ecosystems to such changes. Based on the pollen record, five major vegetation and climate changes could be identified: (1) A shift from alpine desert to alpine steppe indicates a change from cold, dry conditions to warmer and more moist conditions at 14.8 cal. ka BP, (2) alpine steppe with tundra elements points to conditions of higher effective moisture and a stepwise warming climate at 13.6 cal. ka BP, (3) the appearance of high-alpine meadow vegetation indicates a further change towards increased moisture, but with colder temperatures, at 7.0 cal. ka BP, (4) the reoccurrence of alpine steppe with desert elements suggests a return to a significantly colder and drier phase at 6.3 cal. ka BP, and (5) the establishment of alpine steppe-meadow vegetation indicates a change back to relatively moist conditions at 2.2 cal. ka BP. To place the reconstructed climate inferences from the NE Tibetan Plateau into the context of Holocene moisture evolution across the Tibetan Plateau, I applied a five-scale moisture index and average link clustering to all available continuous pollen and non-pollen palaeoclimate records from the Tibetan Plateau, in an attempt to detect coherent regional and temporal patterns of moisture evolution on the Plateau. However, no common temporal or spatial pattern of moisture evolution during the Holocene could be detected, which can be assigned to the complex responses of different proxies to environmental changes in an already very heterogeneous mountain landscape, where minor differences in elevation can result in marked variations in microenvironments. Focusing on the past 200 years, I analysed the sedimentary records (LC6 Lake 29.5°N, 94.3°E, 4132 m asl; and Wuxu Lake 29.9°N, 101.1°E, 3705 m asl) from the southeastern Tibetan Plateau. I found that despite presumed significant temperature increases over that period, pollen and diatom records from the SE Tibetan Plateau reveal only very subtle changes throughout their profiles. The compositional species turnover investigated over the last 200 years appears relatively low in comparison to the species reorganisations during the Holocene. The results indicate that climatically induced ecological thresholds are not yet crossed, but that human activity has an increasing influence, particularly on the terrestrial ecosystem. Forest clearances and reforestation have not caused forest decline in our study area, but a conversion of natural forests to semi-natural secondary forests. The results from the numerical proxy comparison of the two sets of two pairs of Tibetan lakes indicate that the use of different proxies and the work with palaeo-ecological records from different lake types can cause deviant stories of inferred change. Irrespective of the timescale (Holocene or last 200 years) or region (SE or NE Tibetan Plateau) analysed, the agreement in terms of the direction, timing, and magnitude of change between the corresponding terrestrial data sets is generally better than the match between the corresponding lacustrine data sets, suggesting that lacustrine proxies may partly be influenced by in-lake or local catchment processes whereas the terrestrial proxy reflects a more regional climatic signal. The current disaccord on coherent temporal and spatial climate patterns on the Tibetan Plateau can partly be ascribed to the complexity of proxy response and lake systems on the Tibetan Plateau. Therefore, a multi-proxy, multi-site approach is important in order to gain a reliable climate interpretation for the complex mountain landscape of the Tibetan Plateau.}, language = {en} } @misc{HiemerRoesslerScherbaum2010, author = {Hiemer, Stefan and R{\"o}ßler, Dirk and Scherbaum, Frank}, title = {Catalog of Swarm Earthquakes in Vogtland /West Bohemia in 2008/09}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53837}, year = {2010}, abstract = {The document contains the catalog of earthquakes in Vogtland /West Bohemia within the period of 2008/10/19 -to- 2009/03/16. The events were recorded by a seismic mini-array operated by the Institute of Earthsciences, University of Postdam.}, language = {en} } @phdthesis{Swierczynski2012, author = {Swierczynski, Tina}, title = {A 7000 yr runoff chronology from varved sediments of Lake Mondsee (Upper Austria)}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66702}, school = {Universit{\"a}t Potsdam}, year = {2012}, abstract = {The potential increase in frequency and magnitude of extreme floods is currently discussed in terms of global warming and the intensification of the hydrological cycle. The profound knowledge of past natural variability of floods is of utmost importance in order to assess flood risk for the future. Since instrumental flood series cover only the last ~150 years, other approaches to reconstruct historical and pre-historical flood events are needed. Annually laminated (varved) lake sediments are meaningful natural geoarchives because they provide continuous records of environmental changes > 10000 years down to a seasonal resolution. Since lake basins additionally act as natural sediment traps, the riverine sediment supply, which is preserved as detrital event layers in the lake sediments, can be used as a proxy for extreme discharge events. Within my thesis I examined a ~ 8.50 m long sedimentary record from the pre-Alpine Lake Mondsee (Northeast European Alps), which covered the last 7000 years. This sediment record consists of calcite varves and intercalated detrital layers, which range in thickness from 0.05 to 32 mm. Detrital layer deposition was analysed by a combined method of microfacies analysis via thin sections, Scanning Electron Microscopy (SEM), μX-ray fluorescence (μXRF) scanning and magnetic susceptibility. This approach allows characterizing individual detrital event layers and assigning a corresponding input mechanism and catchment. Based on varve counting and controlled by 14C age dates, the main goals of this thesis are (i) to identify seasonal runoff processes, which lead to significant sediment supply from the catchment into the lake basin and (ii) to investigate flood frequency under changing climate boundary conditions. This thesis follows a line of different time slices, presenting an integrative approach linking instrumental and historical flood data from Lake Mondsee in order to evaluate the flood record inferred from Lake Mondsee sediments. The investigation of eleven short cores covering the last 100 years reveals the abundance of 12 detrital layers. Therein, two types of detrital layers are distinguished by grain size, geochemical composition and distribution pattern within the lake basin. Detrital layers, which are enriched in siliciclastic and dolomitic material, reveal sediment supply from the Flysch sediments and Northern Calcareous Alps into the lake basin. These layers are thicker in the northern lake basin (0.1-3.9 mm) and thinner in the southern lake basin (0.05-1.6 mm). Detrital layers, which are enriched in dolomitic components forming graded detrital layers (turbidites), indicate the provenance from the Northern Calcareous Alps. These layers are generally thicker (0.65-32 mm) and are solely recorded within the southern lake basin. In comparison with instrumental data, thicker graded layers result from local debris flow events in summer, whereas thin layers are deposited during regional flood events in spring/summer. Extreme summer floods as reported from flood layer deposition are principally caused by cyclonic activity from the Mediterranean Sea, e.g. July 1954, July 1997 and August 2002. During the last two millennia, Lake Mondsee sediments reveal two significant flood intervals with decadal-scale flood episodes, during the Dark Ages Cold Period (DACP) and the transition from the Medieval Climate Anomaly (MCA) into the Little Ice Age (LIA) suggesting a linkage of transition to climate cooling and summer flood recurrences in the Northeastern Alps. In contrast, intermediate or decreased flood episodes appeared during the MWP and the LIA. This indicates a non-straightforward relationship between temperature and flood recurrence, suggesting higher cyclonic activity during climate transition in the Northeast Alps. The 7000-year flood chronology reveals 47 debris flows and 269 floods, with increased flood activity shifting around 3500 and 1500 varve yr BP (varve yr BP = varve years before present, before present = AD 1950). This significant increase in flood activity shows a coincidence with millennial-scale climate cooling that is reported from main Alpine glacier advances and lower tree lines in the European Alps since about 3300 cal. yr BP (calibrated years before present). Despite relatively low flood occurrence prior to 1500 varve yr BP, floods at Lake Mondsee could have also influenced human life in early Neolithic lake dwellings (5750-4750 cal. yr BP). While the first lake dwellings were constructed on wetlands, the later lake dwellings were built on piles in the water suggesting an early flood risk adaptation of humans and/or a general change of the Late Neolithic Culture of lake-dwellers because of socio-economic reasons. However, a direct relationship between the final abandonment of the lake dwellings and higher flood frequencies is not evidenced.}, language = {en} } @phdthesis{Conradt2013, author = {Conradt, Tobias}, title = {Challenges of regional hydrological modelling in the Elbe River basin : investigations about model fidelity on sub-catchment level}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-65245}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Within a research project about future sustainable water management options in the Elbe River basin, quasi-natural discharge scenarios had to be provided. The semi-distributed eco-hydrological model SWIM was utilised for this task. According to scenario simulations driven by the stochastical climate model STAR, the region would get distinctly drier. However, this thesis focuses on the challenge of meeting the requirement of high model fidelity even for smaller sub-basins. Usually, the quality of the simulations is lower at inner points than at the outlet. Four research paper chapters and the discussion chapter deal with the reasons for local model deviations and the problem of optimal spatial calibration. Besides other assessments, the Markov Chain Monte Carlo method is applied to show whether evapotranspiration or precipitation should be corrected to minimise runoff deviations, principal component analysis is used in an unusual way to evaluate local precipitation alterations by land cover changes, and remotely sensed surface temperatures allow for an independent view on the evapotranspiration landscape. The overall insight is that spatially explicit hydrological modelling of such a large river basin requires a lot of local knowledge. It probably needs more time to obtain such knowledge as is usually provided for hydrological modelling studies.}, language = {en} } @misc{Gassner2012, type = {Master Thesis}, author = {Gassner, Alexandra Carina}, title = {The character of the core-mantle boundary : a systematic study using PcP}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-63590}, school = {Universit{\"a}t Potsdam}, year = {2012}, abstract = {Assuming that liquid iron alloy from the outer core interacts with the solid silicate-rich lower mantle the influence on the core-mantle reflected phase PcP is studied. If the core-mantle boundary is not a sharp discontinuity, this becomes apparent in the waveform and amplitude of PcP. Iron-silicate mixing would lead to regions of partial melting with higher density which in turn reduces the velocity of seismic waves. On the basis of the calculation and interpretation of short-period synthetic seismograms, using the reflectivity and Gauss Beam method, a model space is evaluated for these ultra-low velocity zones (ULVZs). The aim of this thesis is to analyse the behaviour of PcP between 10° and 40° source distance for such models using different velocity and density configurations. Furthermore, the resolution limits of seismic data are discussed. The influence of the assumed layer thickness, dominant source frequency and ULVZ topography are analysed. The Gr{\"a}fenberg and NORSAR arrays are then used to investigate PcP from deep earthquakes and nuclear explosions. The seismic resolution of an ULVZ is limited both for velocity and density contrasts and layer thicknesses. Even a very thin global core-mantle transition zone (CMTZ), rather than a discrete boundary and also with strong impedance contrasts, seems possible: If no precursor is observable but the PcP_model /PcP_smooth amplitude reduction amounts to more than 10\%, a very thin ULVZ of 5 km with a first-order discontinuity may exist. Otherwise, if amplitude reductions of less than 10\% are obtained, this could indicate either a moderate, thin ULVZ or a gradient mantle-side CMTZ. Synthetic computations reveal notable amplitude variations as function of the distance and the impedance contrasts. Thereby a primary density effect in the very steep-angle range and a pronounced velocity dependency in the wide-angle region can be predicted. In view of the modelled findings, there is evidence for a 10 to 13.5 km thick ULVZ 600 km south-eastern of Moscow with a NW-SE extension of about 450 km. Here a single specific assumption about the velocity and density anomaly is not possible. This is in agreement with the synthetic results in which several models create similar amplitude-waveform characteristics. For example, a ULVZ model with contrasts of -5\% VP , -15\% VS and +5\% density explain the measured PcP amplitudes. Moreover, below SW Finland and NNW of the Caspian Sea a CMB topography can be assumed. The amplitude measurements indicate a wavelength of 200 km and a height of 1 km topography, previously also shown in the study by Kampfmann and M{\"u}ller (1989). Better constraints might be provided by a joined analysis of seismological data, mineralogical experiments and geodynamic modelling.}, language = {en} } @phdthesis{Buchhorn2013, author = {Buchhorn, Marcel}, title = {Ground-based hyperspectral and spectro-directional reflectance characterization of Arctic tundra vegetation communities : field spectroscopy and field spectro-goniometry of Siberian and Alaskan tundra in preparation of the EnMAP satellite mission}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-70189}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The Arctic tundra, covering approx. 5.5 \% of the Earth's land surface, is one of the last ecosystems remaining closest to its untouched condition. Remote sensing is able to provide information at regular time intervals and large spatial scales on the structure and function of Arctic ecosystems. But almost all natural surfaces reveal individual anisotropic reflectance behaviors, which can be described by the bidirectional reflectance distribution function (BRDF). This effect can cause significant changes in the measured surface reflectance depending on solar illumination and sensor viewing geometries. The aim of this thesis is the hyperspectral and spectro-directional reflectance characterization of important Arctic tundra vegetation communities at representative Siberian and Alaskan tundra sites as basis for the extraction of vegetation parameters, and the normalization of BRDF effects in off-nadir and multi-temporal remote sensing data. Moreover, in preparation for the upcoming German EnMAP (Environmental Mapping and Analysis Program) satellite mission, the understanding of BRDF effects in Arctic tundra is essential for the retrieval of high quality, consistent and therefore comparable datasets. The research in this doctoral thesis is based on field spectroscopic and field spectro-goniometric investigations of representative Siberian and Alaskan measurement grids. The first objective of this thesis was the development of a lightweight, transportable, and easily managed field spectro-goniometer system which nevertheless provides reliable spectro-directional data. I developed the Manual Transportable Instrument platform for ground-based Spectro-directional observations (ManTIS). The outcome of the field spectro-radiometrical measurements at the Low Arctic study sites along important environmental gradients (regional climate, soil pH, toposequence, and soil moisture) show that the different plant communities can be distinguished by their nadir-view reflectance spectra. The results especially reveal separation possibilities between the different tundra vegetation communities in the visible (VIS) blue and red wavelength regions. Additionally, the near-infrared (NIR) shoulder and NIR reflectance plateau, despite their relatively low values due to the low structure of tundra vegetation, are still valuable information sources and can separate communities according to their biomass and vegetation structure. In general, all different tundra plant communities show: (i) low maximum NIR reflectance; (ii) a weakly or nonexistent visible green reflectance peak in the VIS spectrum; (iii) a narrow "red-edge" region between the red and NIR wavelength regions; and (iv) no distinct NIR reflectance plateau. These common nadir-view reflectance characteristics are essential for the understanding of the variability of BRDF effects in Arctic tundra. None of the analyzed tundra communities showed an even closely isotropic reflectance behavior. In general, tundra vegetation communities: (i) usually show the highest BRDF effects in the solar principal plane; (ii) usually show the reflectance maximum in the backward viewing directions, and the reflectance minimum in the nadir to forward viewing directions; (iii) usually have a higher degree of reflectance anisotropy in the VIS wavelength region than in the NIR wavelength region; and (iv) show a more bowl-shaped reflectance distribution in longer wavelength bands (>700 nm). The results of the analysis of the influence of high sun zenith angles on the reflectance anisotropy show that with increasing sun zenith angles, the reflectance anisotropy changes to azimuthally symmetrical, bowl-shaped reflectance distributions with the lowest reflectance values in the nadir view position. The spectro-directional analyses also show that remote sensing products such as the NDVI or relative absorption depth products are strongly influenced by BRDF effects, and that the anisotropic characteristics of the remote sensing products can significantly differ from the observed BRDF effects in the original reflectance data. But the results further show that the NDVI can minimize view angle effects relative to the contrary spectro-directional effects in the red and NIR bands. For the researched tundra plant communities, the overall difference of the off-nadir NDVI values compared to the nadir value increases with increasing sensor viewing angles, but on average never exceeds 10 \%. In conclusion, this study shows that changes in the illumination-target-viewing geometry directly lead to an altering of the reflectance spectra of Arctic tundra communities according to their object-specific BRDFs. Since the different tundra communities show only small, but nonetheless significant differences in the surface reflectance, it is important to include spectro-directional reflectance characteristics in the algorithm development for remote sensing products.}, language = {en} } @phdthesis{Vogel2013, author = {Vogel, Kristin}, title = {Applications of Bayesian networks in natural hazard assessments}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69777}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Even though quite different in occurrence and consequences, from a modeling perspective many natural hazards share similar properties and challenges. Their complex nature as well as lacking knowledge about their driving forces and potential effects make their analysis demanding: uncertainty about the modeling framework, inaccurate or incomplete event observations and the intrinsic randomness of the natural phenomenon add up to different interacting layers of uncertainty, which require a careful handling. Nevertheless deterministic approaches are still widely used in natural hazard assessments, holding the risk of underestimating the hazard with disastrous effects. The all-round probabilistic framework of Bayesian networks constitutes an attractive alternative. In contrast to deterministic proceedings, it treats response variables as well as explanatory variables as random variables making no difference between input and output variables. Using a graphical representation Bayesian networks encode the dependency relations between the variables in a directed acyclic graph: variables are represented as nodes and (in-)dependencies between variables as (missing) edges between the nodes. The joint distribution of all variables can thus be described by decomposing it, according to the depicted independences, into a product of local conditional probability distributions, which are defined by the parameters of the Bayesian network. In the framework of this thesis the Bayesian network approach is applied to different natural hazard domains (i.e. seismic hazard, flood damage and landslide assessments). Learning the network structure and parameters from data, Bayesian networks reveal relevant dependency relations between the included variables and help to gain knowledge about the underlying processes. The problem of Bayesian network learning is cast in a Bayesian framework, considering the network structure and parameters as random variables itself and searching for the most likely combination of both, which corresponds to the maximum a posteriori (MAP score) of their joint distribution given the observed data. Although well studied in theory the learning of Bayesian networks based on real-world data is usually not straight forward and requires an adoption of existing algorithms. Typically arising problems are the handling of continuous variables, incomplete observations and the interaction of both. Working with continuous distributions requires assumptions about the allowed families of distributions. To "let the data speak" and avoid wrong assumptions, continuous variables are instead discretized here, thus allowing for a completely data-driven and distribution-free learning. An extension of the MAP score, considering the discretization as random variable as well, is developed for an automatic multivariate discretization, that takes interactions between the variables into account. The discretization process is nested into the network learning and requires several iterations. Having to face incomplete observations on top, this may pose a computational burden. Iterative proceedings for missing value estimation become quickly infeasible. A more efficient albeit approximate method is used instead, estimating the missing values based only on the observations of variables directly interacting with the missing variable. Moreover natural hazard assessments often have a primary interest in a certain target variable. The discretization learned for this variable does not always have the required resolution for a good prediction performance. Finer resolutions for (conditional) continuous distributions are achieved with continuous approximations subsequent to the Bayesian network learning, using kernel density estimations or mixtures of truncated exponential functions. All our proceedings are completely data-driven. We thus avoid assumptions that require expert knowledge and instead provide domain independent solutions, that are applicable not only in other natural hazard assessments, but in a variety of domains struggling with uncertainties.}, language = {en} } @phdthesis{Borchert2010, author = {Borchert, Manuela}, title = {Interactions between aqueous fluids and silicate melts : equilibration, partitioning and complexation of trace elements}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-42088}, school = {Universit{\"a}t Potsdam}, year = {2010}, abstract = {The origin and evolution of granites has been widely studied because granitoid rocks constitute a major portion of the Earth's crust. The formation of granitic magma is, besides temperature mainly triggered by the water content of these rocks. The presence of water in magmas plays an important role due to the ability of aqueous fluids to change the chemical composition of the magma. The exsolution of aqueous fluids from melts is closely linked to a fractionation of elements between the two phases. Then, aqueous fluids migrate to shallower parts of the Earth's crust because of it's lower density compared to that of melts and adjacent rocks. This process separates fluids and melts, and furthermore, during the ascent, aqueous fluids can react with the adjacent rocks and alter their chemical signature. This is particularly impor- tant during the formation of magmatic-hydrothermal ore deposits or in the late stages of the evolution of magmatic complexes. For a deeper insight to these processes, it is essential to improve our knowledge on element behavior in such systems. In particular, trace elements are used for these studies and petrogenetic interpretations because, unlike major elements, they are not essential for the stability of the phases involved and often reflect magmatic processes with less ambiguity. However, for the majority of important trace elements, the dependence of the geochemical behavior on temperature, pressure, and in particular on the composition of the system are only incompletely or not at all experimentally studied. Former studies often fo- cus on the determination of fluid-melt partition coefficients (Df/m=cfluid/cmelt) of economically interesting elements, e.g., Mo, Sn, Cu, and there are some partitioning data available for ele- ments that are also commonly used for petrological interpretations. At present, no systematic experimental data on trace element behavior in fluid-melt systems as function of pressure, temperature, and chemical composition are available. Additionally, almost all existing data are based on the analysis of quenched phases. This results in substantial uncertainties, particularly for the quenched aqueous fluid because trace element concentrations may change upon cooling. The objective of this PhD thesis consisted in the study of fluid-melt partition coefficients between aqueous solutions and granitic melts for different trace elements (Rb, Sr, Ba, La, Y, and Yb) as a function of temperature, pressure, salinity of the fluid, composition of the melt, and experimental and analytical approach. The latter included the refinement of an existing method to measure trace element concentrations in fluids equilibrated with silicate melts di- rectly at elevated pressures and temperatures using a hydrothermal diamond-anvil cell and synchrotron radiation X-ray fluorescence microanalysis. The application of this in-situ method enables to avoid the main source of error in data from quench experiments, i.e., trace element concentration in the fluid. A comparison of the in-situ results to data of conventional quench experiments allows a critical evaluation of quench data from this study and literature data. In detail, starting materials consisted of a suite of trace element doped haplogranitic glasses with ASI varying between 0.8 and 1.4 and H2O or a chloridic solution with m NaCl/KCl=1 and different salinities (1.16 to 3.56 m (NaCl+KCl)). Experiments were performed at 750 to 950◦C and 0.2 or 0.5 GPa using conventional quench devices (externally and internally heated pressure vessels) with different quench rates, and at 750◦C and 0.2 to 1.4 GPa with in-situ analysis of the trace element concentration in the fluids. The fluid-melt partitioning data of all studied trace elements show 1. a preference for the melt (Df/m < 1) at all studied conditions, 2. one to two orders of magnitude higher Df/m using chloridic solutions compared to experiments with H2O, 3. a clear dependence on the melt composition for fluid-melt partitioning of Sr, Ba, La, Y, and Yb in experiments using chloridic solutions, 4. quench rate-related differences of fluid-melt partition coefficients of Rb and Sr, and 5. distinctly higher fluid-melt partitioning data obtained from in-situ experiments than from comparable quench runs, particularly in the case of H2O as starting solution. The data point to a preference of all studied trace elements for the melt even at fairly high salinities, which contrasts with other experimental studies, but is supported by data from studies of natural co-genetically trapped fluid and melt inclusions. The in-situ measurements of trace element concentrations in the fluid verify that aqueous fluids will change their composition upon cooling, which is in particular important for Cl free systems. The distinct differences of the in-situ results to quench data of this study as well as to data from the literature signify the im- portance of a careful fluid sampling and analysis. Therefore, the direct measurement of trace element contents in fluids equilibrated with silicate melts at elevated PT conditions represents an important development to obtain more reliable fluid-melt partition coefficients. For further improvement, both the aqueous fluid and the silicate melt need to be analyzed in-situ because partitioning data that are based on the direct measurement of the trace element content in the fluid and analysis of a quenched melt are still not completely free of quench effects. At present, all available data on element complexation in aqueous fluids in equilibrium with silicate melts at high PT are indirectly derived from partitioning data, which involves in these experiments assumptions on the species present in the fluid. However, the activities of chemical components in these partitioning experiments are not well constrained, which is required for the definition of exchange equilibria between melt and fluid species. For example, the melt-dependent variation of partition coefficient observed for Sr imply that this element can not only be complexed by Cl- as suggested previously. The data indicate a more complicated complexation of Sr in the aqueous fluid. To verify this hypothesis, the in-situ setup was also used to determine strontium complexation in fluids equilibrated with silicate melts at desired PT conditions by the application of X-ray absorption near edge structure (XANES) spectroscopy. First results show a strong effect of both fluid and melt composition on the resulting XANES spectra, which indicates different complexation environments for Sr.}, language = {en} } @phdthesis{Creutzfeldt2010, author = {Creutzfeldt, Noah Angelo Benjamin}, title = {The effect of water storages on temporal gravity measurements and the benefits for hydrology}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-48575}, school = {Universit{\"a}t Potsdam}, year = {2010}, abstract = {Temporal gravimeter observations, used in geodesy and geophysics to study variation of the Earth's gravity field, are influenced by local water storage changes (WSC) and - from this perspective - add noise to the gravimeter signal records. At the same time, the part of the gravity signal caused by WSC may provide substantial information for hydrologists. Water storages are the fundamental state variable of hydrological systems, but comprehensive data on total WSC are practically inaccessible and their quantification is associated with a high level of uncertainty at the field scale. This study investigates the relationship between temporal gravity measurements and WSC in order to reduce the hydrological interfering signal from temporal gravity measurements and to explore the value of temporal gravity measurements for hydrology for the superconducting gravimeter (SG) of the Geodetic Observatory Wettzell, Germany. A 4D forward model with a spatially nested discretization domain was developed to simulate and calculate the local hydrological effect on the temporal gravity observations. An intensive measurement system was installed at the Geodetic Observatory Wettzell and WSC were measured in all relevant storage components, namely groundwater, saprolite, soil, top soil and snow storage. The monitoring system comprised also a suction-controlled, weighable, monolith-filled lysimeter, allowing an all time first comparison of a lysimeter and a gravimeter. Lysimeter data were used to estimate WSC at the field scale in combination with complementary observations and a hydrological 1D model. Total local WSC were derived, uncertainties were assessed and the hydrological gravity response was calculated from the WSC. A simple conceptual hydrological model was calibrated and evaluated against records of a superconducting gravimeter, soil moisture and groundwater time series. The model was evaluated by a split sample test and validated against independently estimated WSC from the lysimeter-based approach. A simulation of the hydrological gravity effect showed that WSC of one meter height along the topography caused a gravity response of 52 µGal, whereas, generally in geodesy, on flat terrain, the same water mass variation causes a gravity change of only 42 µGal (Bouguer approximation). The radius of influence of local water storage variations can be limited to 1000 m and 50 \% to 80 \% of the local hydro¬logical gravity signal is generated within a radius of 50 m around the gravimeter. At the Geodetic Observatory Wettzell, WSC in the snow pack, top soil, unsaturated saprolite and fractured aquifer are all important terms of the local water budget. With the exception of snow, all storage components have gravity responses of the same order of magnitude and are therefore relevant for gravity observations. The comparison of the total hydrological gravity response to the gravity residuals obtained from the SG, showed similarities in both short-term and seasonal dynamics. However, the results demonstrated the limitations of estimating total local WSC using hydrological point measurements. The results of the lysimeter-based approach showed that gravity residuals are caused to a larger extent by local WSC than previously estimated. A comparison of the results with other methods used in the past to correct temporal gravity observations for the local hydrological influence showed that the lysimeter measurements improved the independent estimation of WSC significantly and thus provided a better way of estimating the local hydrological gravity effect. In the context of hydrological noise reduction, at sites where temporal gravity observations are used for geophysical studies beyond local hydrology, the installation of a lysimeter in combination with complementary hydrological measurements is recommended. From the hydrological view point, using gravimeter data as a calibration constraint improved the model results in comparison to hydrological point measurements. Thanks to their capacity to integrate over different storage components and a larger area, gravimeters provide generalized information on total WSC at the field scale. Due to their integrative nature, gravity data must be interpreted with great care in hydrological studies. However, gravimeters can serve as a novel measurement instrument for hydrology and the application of gravimeters especially designed to study open research questions in hydrology is recommended.}, language = {en} } @misc{CrisologoHeistermann2020, author = {Crisologo, Irene and Heistermann, Maik}, title = {Using ground radar overlaps to verify the retrieval of calibration bias estimates from spaceborne platforms}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {863}, issn = {1866-8372}, doi = {10.25932/publishup-45963}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-459630}, pages = {17}, year = {2020}, abstract = {Many institutions struggle to tap into the potential of their large archives of radar reflectivity: these data are often affected by miscalibration, yet the bias is typically unknown and temporally volatile. Still, relative calibration techniques can be used to correct the measurements a posteriori. For that purpose, the usage of spaceborne reflectivity observations from the Tropical Rainfall Measuring Mission (TRMM) and Global Precipitation Measurement (GPM) platforms has become increasingly popular: the calibration bias of a ground radar (GR) is estimated from its average reflectivity difference to the spaceborne radar (SR). Recently, Crisologo et al. (2018) introduced a formal procedure to enhance the reliability of such estimates: each match between SR and GR observations is assigned a quality index, and the calibration bias is inferred as a quality-weighted average of the differences between SR and GR. The relevance of quality was exemplified for the Subic S-band radar in the Philippines, which is greatly affected by partial beam blockage. The present study extends the concept of quality-weighted averaging by accounting for path-integrated attenuation (PIA) in addition to beam blockage. This extension becomes vital for radars that operate at the C or X band. Correspondingly, the study setup includes a C-band radar that substantially overlaps with the S-band radar. Based on the extended quality-weighting approach, we retrieve, for each of the two ground radars, a time series of calibration bias estimates from suitable SR overpasses. As a result of applying these estimates to correct the ground radar observations, the consistency between the ground radars in the region of overlap increased substantially. Furthermore, we investigated if the bias estimates can be interpolated in time, so that ground radar observations can be corrected even in the absence of prompt SR overpasses. We found that a moving average approach was most suitable for that purpose, although limited by the absence of explicit records of radar maintenance operations.}, language = {en} } @misc{AyzelSchefferHeistermann2020, author = {Ayzel, Georgy and Scheffer, Tobias and Heistermann, Maik}, title = {RainNet v1.0}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {964}, issn = {1866-8372}, doi = {10.25932/publishup-47294}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472942}, pages = {16}, year = {2020}, abstract = {In this study, we present RainNet, a deep convolutional neural network for radar-based precipitation nowcasting. Its design was inspired by the U-Net and SegNet families of deep learning models, which were originally designed for binary segmentation tasks. RainNet was trained to predict continuous precipitation intensities at a lead time of 5min, using several years of quality-controlled weather radar composites provided by the German Weather Service (DWD). That data set covers Germany with a spatial domain of 900km × 900km and has a resolution of 1km in space and 5min in time. Independent verification experiments were carried out on 11 summer precipitation events from 2016 to 2017. In order to achieve a lead time of 1h, a recursive approach was implemented by using RainNet predictions at 5min lead times as model inputs for longer lead times. In the verification experiments, trivial Eulerian persistence and a conventional model based on optical flow served as benchmarks. The latter is available in the rainymotion library and had previously been shown to outperform DWD's operational nowcasting model for the same set of verification events. RainNet significantly outperforms the benchmark models at all lead times up to 60min for the routine verification metrics mean absolute error (MAE) and the critical success index (CSI) at intensity thresholds of 0.125, 1, and 5mm h⁻¹. However, rainymotion turned out to be superior in predicting the exceedance of higher intensity thresholds (here 10 and 15mm h⁻¹). The limited ability of RainNet to predict heavy rainfall intensities is an undesirable property which we attribute to a high level of spatial smoothing introduced by the model. At a lead time of 5min, an analysis of power spectral density confirmed a significant loss of spectral power at length scales of 16km and below. Obviously, RainNet had learned an optimal level of smoothing to produce a nowcast at 5min lead time. In that sense, the loss of spectral power at small scales is informative, too, as it reflects the limits of predictability as a function of spatial scale. Beyond the lead time of 5min, however, the increasing level of smoothing is a mere artifact - an analogue to numerical diffusion - that is not a property of RainNet itself but of its recursive application. In the context of early warning, the smoothing is particularly unfavorable since pronounced features of intense precipitation tend to get lost over longer lead times. Hence, we propose several options to address this issue in prospective research, including an adjustment of the loss function for model training, model training for longer lead times, and the prediction of threshold exceedance in terms of a binary segmentation task. Furthermore, we suggest additional input data that could help to better identify situations with imminent precipitation dynamics. The model code, pretrained weights, and training data are provided in open repositories as an input for such future studies.}, language = {en} } @article{RitterAngelesBurgosBoeckmannetal.2018, author = {Ritter, Christoph and {\´A}ngeles Burgos, Mar{\´i}a and B{\"o}ckmann, Christine and Mateos, David and Lisok, Justyna and Markowicz, Krzysztof M. and Moroni, Beatrice and Cappelletti, David and Udisti, Roberto and Maturilli, Marion and Neuber, Roland}, title = {Microphysical properties and radiative impact of an intense biomass burning aerosol event measured over Ny-angstrom lesund, Spitsbergen in July 2015}, series = {Tellus - Series B, Chemical and Physical Meteorology}, volume = {70}, journal = {Tellus - Series B, Chemical and Physical Meteorology}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {1600-0889}, doi = {10.1080/16000889.2018.1539618}, pages = {23}, year = {2018}, abstract = {In this work, an evaluation of an intense biomass burning event observed over Ny-angstrom lesund (Spitsbergen, European Arctic) in July 2015 is presented. Data from the multi-wavelengths Raman-lidar KARL, a sun photometer and radiosonde measurements are used to derive some microphysical properties of the biomass burning aerosol as size distribution, refractive index and single scattering albedo at different relative humidities. Predominantly particles in the accumulation mode have been found with a bi-modal distribution and dominance of the smaller mode. Above 80\% relative humidity, hygroscopic growth in terms of an increase of particle diameter and a slight decrease of the index of refraction (real and imaginary part) has been found. Values of the single scattering albedo around 0.9 both at 355nm and 532nm indicate some absorption by the aerosol. Values of the lidar ratio are around 26sr for 355nm and around 50sr for 532nm, almost independent of the relative humidity. Further, data from the photometer and surface radiation values from the local baseline surface radiation network (BSRN) have been applied to derive the radiative impact of the biomass burning event purely from observational data by comparison with a clear background day. We found a strong cooling for the visible radiation and a slight warming in the infra-red. The net aerosol forcing, derived by comparison with a clear background day purely from observational data, obtained a value of -95 W/m(2) per unit AOD500.}, language = {en} } @misc{GeissmanJolivetRusmoreetal.2019, author = {Geissman, John and Jolivet, Laurent and Rusmore, Margi and Niemi, Nathan and Schildgen, Taylor F.}, title = {Thank you to our 2018 peer reviewers}, series = {Tectonics}, volume = {38}, journal = {Tectonics}, number = {4}, publisher = {Hoboken}, address = {Wiley}, issn = {0278-7407}, doi = {10.1029/2019TC005595}, pages = {1159 -- 1163}, year = {2019}, abstract = {An essential, respected, and critical aspect of the modern practice of science and scientific publishing is peer review. The process of peer review facilitates best practices in scientific conduct and communication, ensuring that manuscripts published are as accurate, valuable, and clearly communicated. The over 216 papers published in Tectonics in 2018 benefit from the time, effort, and expertise of our reviewers who have provided thoughtfully considered advice on each manuscript. This role is critical to advancing our understanding of the evolution of the continents and their margins, as these reviews lead to even clearer and higher-quality papers. In 2018, the over 443 papers submitted to Tectonics were the beneficiaries of more than 1,010 reviews provided by 668 members of the tectonics community and related disciplines. To everyone who has volunteered their time and intellect to peer reviewing, thank you for helping Tectonics and all other AGU Publications provide the best science possible.}, language = {en} } @article{RolfPauleitWiggering2018, author = {Rolf, Werner and Pauleit, Stephan and Wiggering, Hubert}, title = {A stakeholder approach, door opener for farmland and multifunctionality in urban green infrastructure}, series = {Urban forestry \& urban greening}, volume = {40}, journal = {Urban forestry \& urban greening}, publisher = {Urban \& Fischer}, address = {Jena}, issn = {1618-8667}, doi = {10.1016/j.ufug.2018.07.012}, pages = {73 -- 83}, year = {2018}, abstract = {During the last years Urban Green Infrastructure (UGI) has evolved as a research focus across Europe. UGI can be understood as a multifunctional network of different urban green spaces and elements contributing to urban benefits. Urban agriculture has gained increasing research interest in this context. While a strong focus has been made on functions and benefits of small scale activities, the question is still open, whether these findings can be up-scaled and transferred to the farmland scale. Furthermore, multifunctionality of urban and peri-urban agriculture is rarely being considered in the landscape context. This research aims to address these gaps and harnesses the question if agricultural landscapes - which in many European metropolitan regions provide significant spatial potential - can contribute to UGI as multifunctional green spaces. This work considers multifunctionality qualitatively based on stakeholder opinion, using a participatory research approach. This study provides new insights in peri-urban farmland potentials for UGI development, resulting into a strategy framework. Furthermore, it reflects on the role of the stakeholder involvement for `multifunctionality planning´. It suggests that it helps to define meaningful bundles of intertwined functions that interact on different scales, helping to deal with non-linearity of multiple functions and to better manage them simultaneously.}, language = {en} } @article{ZhangHuangZhangetal.2019, author = {Zhang, Yang and Huang, Wentao and Zhang, Yuanyuan and Poujol, Marc and Guillot, Stephane and Roperch, Pierrick and Dupont-Nivet, Guillaume and Guo, Zhaojie}, title = {Detrital zircon provenance comparison between the Paleocene-Eocene Nangqian-Xialaxiu and Gongjue basins: New insights for Cenozoic paleogeographic evolution of the eastern Tibetan Plateau}, series = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, volume = {533}, journal = {Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0031-0182}, doi = {10.1016/j.palaeo.2019.109241}, pages = {19}, year = {2019}, abstract = {Paleogeographic reconstructions of terranes can greatly benefit from the provenance analysis of sediments. A series of Cenozoic basins provide key sedimentary archives for investigating the growth of the Tibetan Plateau, yet the provenance of the sediments in these basins has never been constrained robustly. Here we report sedimentary petrological and detrital zircon geochronological data from the Paleocene-Eocene Nangqian-Xialaxiu and Gongjue basins. Sandstone detrital modes and zircon morphology suggest that the samples collected in these two basins were sourced from recycled orogen. Detrital zircon geochronology indicates that sediments in the Nangqian-Xialaxiu Basin are characterized by two distinct age populations at 220-280 Ma and 405-445 Ma. In contrast, three predominant age populations of 207-256 Ma, 423-445 Ma, and 1851-1868 Ma, and two subordinate age populations of similar to 50 Ma and similar to 2500 Ma, are recognized in the Gongjue Basin. Comparison with detrital zircon ages from the surrounding terranes suggests that sediments in the Nangqian-Xialaxiu Basin come from the neighboring thrust belts, whereas sediments from the Gongjue Basin are predominantly derived from the distant Songpan-Ganzi Terrane with minor contribution from the surrounding areas. A three-stage Cenozoic evolution of the eastern Tibetan Plateau is proposed. During the Paleocene, the Nangqian-Xialaxiu Basin appeared as a set of small intermontane sub-basins and received plentiful sediments from the neighboring mountain belts; during the Eocene, the Gongjue Basin kept a relatively low altitude and was a depression at the edge of a proto-Plateau; since the Oligocene, the Tibetan Plateau further uplifted and the marginal Gongjue Basin was involved in the Tibetan interior orogeny, indicating the eastward propagation of the Tibetan Plateau.}, language = {en} } @article{BerkesiCzupponSzaboetal.2018, author = {Berkesi, Marta and Czuppon, Gyorgy and Szabo, Csaba and Kovacs, Istvan and Ferrero, Silvio and Boiron, Marie-Christine and Peiffert, Chantal}, title = {Pargasite in fluid inclusions of mantle xenoliths from northeast Australia (Mt. Quincan)}, series = {Chemical geology : official journal of the European Association for Geochemistry}, volume = {508}, journal = {Chemical geology : official journal of the European Association for Geochemistry}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0009-2541}, doi = {10.1016/j.chemgeo.2018.06.022}, pages = {182 -- 196}, year = {2018}, abstract = {Three spinel lherzolite xenoliths from Mt. Quincan (Queensland, northeastern Australia) were studied with special attention to their enclosed fluid inclusions. The xenoliths are deformed, have porphyroclastic textures and overall show very similar petrographic features. The only significant difference is manifested in the abundance of fluid inclusions in the samples, mostly in orthopyroxene porphyroclasts. Xenolith JMTQ11 is fluid inclusion-free, whereas xenolith JMTQ20 shows a high abundance of fluid inclusions (fluid inclusion-rich). Xenolith JMTQ45 represents a transitional state between the previous two, as it contains only a small amount of fluid inclusions (fluid inclusion-bearing). Previous studies revealed that these xenoliths and the entrapped fluid inclusions represent a former addition of a MORB-type fluid to the pre-existing lithosphere, resulting from asthenosphere upwelling. There is a progressive enrichment in LREE, Nb, Sr and Ti from the fluid inclusion-free xenolith through the fluid inclusion-bearing one to the fluid inclusion-rich lherzolite. This suggests an increase in the extent of the interaction between the fluid-rich melt and the lherzolite wallrock. In addition, the same interaction is considered to be responsible for the formation of pargasitic amphibole as well. The presence of fluid inclusions indicates fluid migration at mantle depth, and their association with exsolution lamellae in orthopyroxene suggests fluid entrapment following the continental rifting (thermal relaxation) during cooling. A series of analyses, including microthermometry coupled with Raman spectroscopy, FTIR hyperspectral imaging, and Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) was carried out on the fluid inclusions. Based on the results, the entrapped high-density fluid is composed of 7589 mol\% CO2, 918 mol\% H2O, 0.11.7 mol\% N-2 and <= 0.5 mol\% H2S with dissolved trace elements (melt component). Our findings suggest that the metasomatic fluid phase could have been either a fluid/fluid-rich silicate melt released from the deeper asthenosphere, or a coexisting incipient fluid-rich silicate melt. Further cooling, possibly due to thermal relaxation and the upward migration of the fluid phase, caused the investigated lherzolites to reach pargasite stability conditions. We conclude that pargasite, even if only present in very limited modal proportions, can be a common phase at spinel lherzolite stability in the lithospheric upper mantle in continental rift back-arc settings. Studies of fluid inclusions indicate that significant CO2 release from the asthenosphere in a continental rifting environment is resulting from asthenosphere upwelling and its addition to the lithospheric mantle together with fluid-rich melt lherzolite interaction that leaves a CO2-rich fluid behind.}, language = {en} }