@article{CaoHerzschuhNietal.2015, author = {Cao, Xianyong and Herzschuh, Ulrike and Ni, Jian and Zhao, Yan and B{\"o}hmer, Thomas}, title = {Spatial and temporal distributions of major tree taxa in eastern continental Asia during the last 22,000 years}, series = {The Holocene : an interdisciplinary journal focusing on recent environmental change}, volume = {25}, journal = {The Holocene : an interdisciplinary journal focusing on recent environmental change}, number = {1}, publisher = {Sage Publ.}, address = {London}, issn = {0959-6836}, doi = {10.1177/0959683614556385}, pages = {79 -- 91}, year = {2015}, abstract = {This study investigates the spatial and temporal distributions of 14 key arboreal taxa and their driving forces during the last 22,000 calendar years before ad 1950 (kyr BP) using a taxonomically harmonized and temporally standardized fossil pollen dataset with a 500-year resolution from the eastern part of continental Asia. Logistic regression was used to estimate pollen abundance thresholds for vegetation occurrence (presence or dominance), based on modern pollen data and present ranges of 14 taxa in China. Our investigation reveals marked changes in spatial and temporal distributions of the major arboreal taxa. The thermophilous (Castanea, Castanopsis, Cyclobalanopsis, Fagus, Pterocarya) and eurythermal (Juglans, Quercus, Tilia, Ulmus) broadleaved tree taxa were restricted to the current tropical or subtropical areas of China during the Last Glacial Maximum (LGM) and spread northward since c. 14.5kyr BP. Betula and conifer taxa (Abies, Picea, Pinus), in contrast, retained a wider distribution during the LGM and showed no distinct expansion direction during the Late Glacial. Since the late mid-Holocene, the abundance but not the spatial extent of most trees decreased. The changes in spatial and temporal distributions for the 14 taxa are a reflection of climate changes, in particular monsoonal moisture, and, in the late Holocene, human impact. The post-LGM expansion patterns in eastern continental China seem to be different from those reported for Europe and North America, for example, the westward spread for eurythermal broadleaved taxa.}, language = {en} } @article{SchwabGarcinSachseetal.2015, author = {Schwab, Valerie F. and Garcin, Yannick and Sachse, Dirk and Todou, Gilbert and Sene, Olivier and Onana, Jean-Michel and Achoundong, Gaston and Gleixner, Gerd}, title = {Effect of aridity on delta C-13 and delta D values of C-3 plant- and C-4 graminoid-derived leaf wax lipids from soils along an environmental gradient in Cameroon (Western Central Africa)}, series = {Organic geochemistry : the international journal for rapid publication of current research in organic geochemistry and biochemistry}, volume = {78}, 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.2014.09.007}, pages = {99 -- 109}, year = {2015}, abstract = {The observation that the hydrogen isotope composition (delta D) of leaf wax lipids is determined mainly by precipitation delta D values, has resulted in the application of these biomarkers to reconstruct paleoclimate from geological records. However, because the delta D values of leaf wax lipids are additionally affected by vegetation type and ecosystem evapotranspiration, paleoclimatic reconstruction remains at best semi-quantitative. Here, we used published results for the carbon isotope composition (delta C-13) of n-alkanes in common plants along a latitudinal gradient in C-3/C-4 vegetation and relative humidity in Cameroon and demonstrated that pentacyclic triterpene methyl ethers (PTMEs) and n-C-29 and n-C-31 in the same soil, derived mainly from C-4 graminoids (e.g. grass) and C-3 plants (e.g. trees and shrubs), respectively. We found that the delta D values of soil n-C-27, n-C29 and n-C-31, and PTMEs correlated significantly with surface water delta D values, supporting previous observations that leaf wax lipid delta D values are an effective proxy for reconstructing precipitation delta D values even if plant types changed significantly. The apparent fractionation (epsilon(app)) between leaf wax lipid and precipitation delta D values remained relatively constant for C-3-derived long chain n-alkanes, whereas eapp of C-4-derived PTMEs decreased by 20 parts per thousand along the latitudinal gradient encompassing a relative humidity range from 80\% to 45\%. Our results indicate that PTME delta D values derived from C-4 graminoids may be a more reliable paleo-ecohydrological proxy for ecosystem evapotranspiration within tropical and sub-tropical Africa than n-alkane delta D values, the latter being a better proxy for surface water delta D values. We suggest that vegetation changes associated with different plant water sources and/or difference in timing of leaf wax synthesis between C-3 trees of the transitional class and C-3 shrubs of the savanna resulted in a D depletion in soil long chain n-alkanes, thereby counteracting the effect of evapotranspiration D enrichment along the gradient. In contrast, evaporative D enrichment of leaf and soil water was significant enough to be recorded in the delta D values of PTMEs derived from C-4 graminoids, likely because PTMEs recorded the hydrogen isotopic composition of the same vegetation type.}, language = {en} } @article{QuintanaArimBadosaetal.2015, author = {Quintana, Xavier D. and Arim, Matias and Badosa, Anna and Maria Blanco, Jose and Boix, Dani and Brucet, Sandra and Compte, Jordi and Egozcue, Juan J. and de Eyto, Elvira and Gaedke, Ursula and Gascon, Stephanie and Gil de Sola, Luis and Irvine, Kenneth and Jeppesen, Erik and Lauridsen, Torben L. and Lopez-Flores, Rocio and Mehner, Thomas and Romo, Susana and Sondergaard, Martin}, title = {Predation and competition effects on the size diversity of aquatic communities}, series = {Aquatic sciences : research across boundaries}, volume = {77}, journal = {Aquatic sciences : research across boundaries}, number = {1}, publisher = {Springer}, address = {Basel}, issn = {1015-1621}, doi = {10.1007/s00027-014-0368-1}, pages = {45 -- 57}, year = {2015}, abstract = {Body size has been widely recognised as a key factor determining community structure in ecosystems. We analysed size diversity patterns of phytoplankton, zooplankton and fish assemblages in 13 data sets from freshwater and marine sites with the aim to assess whether there is a general trend in the effect of predation and resource competition on body size distribution across a wide range of aquatic ecosystems. We used size diversity as a measure of the shape of size distribution. Size diversity was computed based on the Shannon-Wiener diversity expression, adapted to a continuous variable, i.e. as body size. Our results show that greater predation pressure was associated with reduced size diversity of prey at all trophic levels. In contrast, competition effects depended on the trophic level considered. At upper trophic levels (zooplankton and fish), size distributions were more diverse when potential resource availability was low, suggesting that competitive interactions for resources promote diversification of aquatic communities by size. This pattern was not found for phytoplankton size distributions where size diversity mostly increased with low zooplankton grazing and increasing nutrient availability. Relationships we found were weak, indicating that predation and competition are not the only determinants of size distribution. Our results suggest that predation pressure leads to accumulation of organisms in the less predated sizes, while resource competition tends to favour a wider size distribution.}, language = {en} } @article{WannerElmerSommeretal.2015, author = {Wanner, Manfred and Elmer, Michael and Sommer, Michael and Funk, Roger and Puppe, Daniel}, title = {Testate amoebae colonizing a newly exposed land surface are of airborne origin}, series = {Ecological indicators : integrating monitoring, assessment and management}, volume = {48}, journal = {Ecological indicators : integrating monitoring, assessment and management}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1470-160X}, doi = {10.1016/j.ecolind.2014.07.037}, pages = {55 -- 62}, year = {2015}, abstract = {We hypothesized that at the very beginning of terrestrial ecosystem development, airborne testate amoebae play a pivotal role in facilitating organismic colonization and related soil processes. We, therefore, analyzed size and quantity of airborne testate amoebae and immigration and colonization success of airborne testate amoebae on a new land surface (experimental site "Chicken Creek", artificial post-mining water catchment). Within an altogether 91-day exposure of 70 adhesive traps, 12 species of testate amoebae were identified to be of airborne origin. Phryganella acropodia (51\% of all individuals found, diameter about 35-45 mu m) and Centropyxis sphagnicola (23\% of all individuals found, longest axis about 55-68 mu m), occurred most frequently in the adhesive traps. We extrapolated an aerial amoeba deposition of 61 individuals d(-1) m(-2) (living and dead individuals combined). Although it would be necessary to have a longer sequence (some additional years), our analysis of the "target substrate" of aerial immigration (catchment site) may point to a shift from a stochastic (variable) beginning of community assembly to a more deterministic (stable) course. This shift was assigned to an age of seven years of initial soil development. Although experienced specialists are necessary to conduct these time-consuming studies, the presented data suggest that terrestrial amoebae are suitable indicators for initial ecosystem development and utilization.}, language = {en} } @misc{MischkeZhangFan2015, author = {Mischke, Steffen and Zhang, Chengjun and Fan, Rong}, title = {Early to mid-Holocene lake high-stand sediments at Lake Donggi Cona, northeastern Tibetan Plateau, China -}, series = {Quaternary research : an interdisciplinary journal}, volume = {83}, journal = {Quaternary research : an interdisciplinary journal}, number = {1}, publisher = {Elsevier}, address = {San Diego}, issn = {0033-5894}, doi = {10.1016/j.yqres.2014.06.005}, pages = {256 -- 258}, year = {2015}, language = {en} } @article{JaraMunozMelnick2015, author = {Jara Mu{\~n}oz, Julius and Melnick, Daniel}, title = {Unraveling sea-level variations and tectonic uplift in wave-built marine terraces, Santa Maria Island, Chile}, series = {Quaternary research : an interdisciplinary journal}, volume = {83}, journal = {Quaternary research : an interdisciplinary journal}, number = {1}, publisher = {Elsevier}, address = {San Diego}, issn = {0033-5894}, doi = {10.1016/j.yqres.2014.10.002}, pages = {216 -- 228}, year = {2015}, abstract = {The architecture of coastal sequences in tectonically-active regions results mostly from a combination of sea-level and land-level changes. The objective of this study is to unravel these signals by combining sequence stratigraphy and sedimentology of near-shore sedimentary sequences in wave-built terraces. We focus on Santa Maria Island at the south-central Chile margin, which hosts excellent exposures of coastal sediments from Marine Isotope Stage 3. A novel method based on statistical analysis of grain-size distributions coupled with fades descriptions provided a detailed account of transgressive-regressive cycles. Radiocarbon ages from paleosols constrain the chronology between >53 and similar to 31 cal ka BP. Because the influence of glaciations can be neglected, we calculated relative sea-level curves by tying the onset of deposition on a bedrock abrasion platform to a global sea-level curve. The observed depositional cycles match those predicted for uplift rates between 1.2 and 1.8 m/ka. The studied sedimentary units represent depositional cycles that resulted in reoccupation events of an existing marine terrace. Our study demonstrates wave-built marine terrace deposits along clastic shorelines in temperate regions can be used to distinguish between tectonic uplift and climate-induced sea-level changes.}, language = {en} } @article{ZhangChenZhouetal.2015, author = {Zhang, Yanqiu and Chen, Daizhao and Zhou, Xiqiang and Guo, Zenghui and Wei, Wenwen and Mutti, Maria}, title = {Depositional facies and stratal cyclicity of dolomites in the Lower Qiulitag Group (Upper Cambrian) in northwestern Tarim Basin, NW China}, series = {Facies : an international journal of palaeontology, sedimentology, geology}, volume = {61}, journal = {Facies : an international journal of palaeontology, sedimentology, geology}, number = {1}, publisher = {Springer}, address = {New York}, issn = {0172-9179}, doi = {10.1007/s10347-014-0417-1}, pages = {24}, year = {2015}, abstract = {The Upper Cambrian Lower Qiulitag Group in the Tarim Basin, NW China, is overwhelmingly composed of cyclic dolomites. Based on extensive field investigations and facies analysis from four outcrop sections in the Bachu-Keping area, northwestern Tarim Basin, four main types of facies are recognized: open-marine subtidal, restricted shallow subtidal, intertidal, and supratidal facies, and these are further subdivided into ten lithofacies. In general, these facies are vertically arranged into shallowing-upward, metre-scale cycles. These cycles are commonly composed of a thin basal horizon reflecting abrupt deepening, and a thicker upper succession showing gradual shallowing upwards. Based on the vertical facies arrangements and changes across boundary surfaces, two types of cycle: peritidal and shallow subtidal cycle, are further identified. The peritidal cycles, predominating over the lower-middle Lower Qiulitag Group, commence with shallow subtidal to lower intertidal facies and are capped by inter-supratidal facies. In contrast, the shallow subtidal cycles, dominating the upper Lower Qiulitag Group, are capped by shallow-subtidal facies. Based on vertical lithofacies variations, cycle stacking patterns, and accommodation variations revealed by Fischer plots, six larger-scale third-order depositional sequences (Sq1-Sq6) are recognized. These sequences generally consist of a lower transgressive and an upper regressive systems tract. The transgressive tracts are dominated by thicker-than-average cycles, indicating an overall accommodation increase, whereas the regressive tracts are characterized by thinner-than-average peritidal cycles, indicating an overall accommodation decrease. The sequence boundaries are characterized by transitional zones of stacked thinner-than-average cycles, rather than by a single surface. These sequences can further be grouped into lower-order sequence sets: the lower and upper sequence sets. The lower sequence set, including Sq1-Sq3, is characterized by peritidal facies-dominated sequences and a progressive decrease in accommodation space, indicating a longer-term fall in sea level. In contrast, the upper sequence set (Sq4-Sq6) is characterized by subtidal facies-dominated sequences and a progressive increase in accommodation space, indicating a longer-term rise in sea level.}, language = {en} } @article{CifelliBallatoAlimohammadianetal.2015, author = {Cifelli, Francesca and Ballato, Paolo and Alimohammadian, Habib and Sabouri, Jafar and Mattei, Massimo}, title = {Tectonic magnetic lineation and oroclinal bending of the Alborz range: Implications on the Iran-Southern Caspian geodynamics}, series = {Tectonics}, volume = {34}, journal = {Tectonics}, number = {1}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0278-7407}, doi = {10.1002/2014TC003626}, pages = {116 -- 132}, year = {2015}, abstract = {In this study we use the anisotropy of magnetic susceptibility (AMS) and paleomagnetic data for deciphering the origin of magnetic lineation in weakly deformed sedimentary rocks and for evaluating oroclinal processes within the Arabia-Eurasia collision zone. In particular, we have analyzed the Miocene Upper Red Formation (URF) from the outer curved front of the southern Central Alborz Mountains of north Iran, to test for the first time with paleomagnetic data the origin (primary versus secondary) of this orogenic arc. AMS data document the existence of a magnetic lineation parallel to the orientation of the major tectonic structures, which vary along strike from WNW to ENE. These directions are highly oblique to the paleoflow directions and hence suggest that the magnetic lineation in the URF was produced by compressional deformation during layer-parallel shortening. In addition, our paleomagnetic data document clockwise and anticlockwise rotations along vertical axis for the western and eastern sectors of the Central Alborz Mountains, respectively. Combined, our results suggest that the orogen represents an orocline, which formed not earlier than circa 7.6Ma most likely through bending processes caused by the relative motion between the rigid crustal blocks of the collision zone. Moreover, our study provides new insights into the Iran-Southern Caspian Basin kinematic evolution suggesting that the present-day SW motion of the South Caspian Basin with respect to Central Iran postdates oroclinal bending and hence cannot be as old as late Miocene to early Pliocene but a rather recent configuration (i.e., 3 to <1Ma).}, language = {en} } @article{HuangDupontNivetLippertetal.2015, author = {Huang, Wentao and Dupont-Nivet, Guillaume and Lippert, Peter C. and van Hinsbergen, Douwe J. J. and Dekkers, Mark J. and Guo, Zhaojie and Waldrip, Ross and Li, Xiaochun and Zhang, Xiaoran and Liu, Dongdong and Kapp, Paul}, title = {Can a primary remanence be retrieved from partially remagnetized Eocence volcanic rocks in the Nanmulin Basin (southern Tibet) to date the India-Asia collision?}, series = {Journal of geophysical research : Solid earth}, volume = {120}, journal = {Journal of geophysical research : Solid earth}, number = {1}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9313}, doi = {10.1002/2014JB011599}, pages = {42 -- 66}, year = {2015}, abstract = {Paleomagnetic dating of the India-Asia collision hinges on determining the Paleogene latitude of the Lhasa terrane (southern Tibet). Reported latitudes range from 5 degrees N to 30 degrees N, however, leading to contrasting paleogeographic interpretations. Here we report new data from the Eocene Linzizong volcanic rocks in the Nanmulin Basin, which previously yielded data suggesting a low paleolatitude (similar to 10 degrees N). New zircon U-Pb dates indicate an age of similar to 52Ma. Negative fold tests, however, demonstrate that the isolated characteristic remanent magnetizations, with notably varying inclinations, are not primary. Rock magnetic analyses, end-member modeling of isothermal remanent magnetization acquisition curves, and petrographic observations are consistent with variable degrees of posttilting remagnetization due to low-temperature alteration of primary magmatic titanomagnetite and the formation of secondary pigmentary hematite that unblock simultaneously. Previously reported paleomagnetic data from the Nanmulin Basin implying low paleolatitude should thus not be used to estimate the time and latitude of the India-Asia collision. We show that the paleomagnetic inclinations vary linearly with the contribution of secondary hematite to saturation isothermal remanent magnetization. We tentatively propose a new method to recover a primary remanence with inclination of 38.1 degrees (35.7 degrees, 40.5 degrees) (95\% significance) and a secondary remanence with inclination of 42.9 degrees (41.5 degrees,44.4 degrees) (95\% significance). The paleolatitude defined by the modeled primary remanence21 degrees N (19.8 degrees N, 23.1 degrees N)is consistent with the regional compilation of published results from pristine volcanic rocks and sedimentary rocks of the upper Linzizong Group corrected for inclination shallowing. The start of the Tibetan Himalaya-Asia collision was situated at similar to 20 degrees N and took place by similar to 50Ma.}, language = {en} } @article{HuangvanHinsbergenDekkersetal.2015, author = {Huang, Wentao and van Hinsbergen, Douwe J. J. and Dekkers, Mark J. and Garzanti, Eduardo and Dupont-Nivet, Guillaume and Lippert, Peter C. and Li, Xiaochun and Maffione, Marco and Langereis, Cor G. and Hu, Xiumian and Guo, Zhaojie and Kapp, Paul}, title = {Paleolatitudes of the Tibetan Himalaya from primary and secondary magnetizations of Jurassic to Lower Cretaceous sedimentary rocks}, series = {Geochemistry, geophysics, geosystems}, volume = {16}, journal = {Geochemistry, geophysics, geosystems}, number = {1}, publisher = {American Geophysical Union}, address = {Washington}, issn = {1525-2027}, doi = {10.1002/2014GC005624}, pages = {77 -- 100}, year = {2015}, abstract = {The Tibetan Himalaya represents the northernmost continental unit of the Indian plate that collided with Asia in the Cenozoic. Paleomagnetic studies on the Tibetan Himalaya can help constrain the dimension and paleogeography of "Greater India,' the Indian plate lithosphere that subducted and underthrusted below Asia after initial collision. Here we present a paleomagnetic investigation of a Jurassic (limestones) and Lower Cretaceous (volcaniclastic sandstones) section of the Tibetan Himalaya. The limestones yielded positive fold test, showing a prefolding origin of the isolated remanent magnetizations. Detailed paleomagnetic analyses, rock magnetic tests, end-member modeling of acquisition curves of isothermal remanent magnetization, and petrographic investigation reveal that the magnetic carrier of the Jurassic limestones is authigenic magnetite, whereas the dominant magnetic carrier of the Lower Cretaceous volcaniclastic sandstones is detrital magnetite. Our observations lead us to conclude that the Jurassic limestones record a prefolding remagnetization, whereas the Lower Cretaceous volcaniclastic sandstones retain a primary remanence. The volcaniclastic sandstones yield an Early Cretaceous paleolatitude of 55.5 degrees S [52.5 degrees S, 58.6 degrees S] for the Tibetan Himalaya, suggesting it was part of the Indian continent at that time. The size of "Greater India' during Jurassic time cannot be estimated from these limestones. Instead, a paleolatitude of the Tibetan Himalaya of 23.8 degrees S [21.8 degrees S, 26.1 degrees S] during the remagnetization process is suggested. It is likely that the remagnetization, caused by the oxidation of early diagenetic pyrite to magnetite, was induced during 103-83 or 77-67 Ma. The inferred paleolatitudes at these two time intervals imply very different tectonic consequences for the Tibetan Himalaya.}, language = {en} } @article{DallmeyerClaussenFischeretal.2015, author = {Dallmeyer, A. and Claussen, M. and Fischer, N. and Haberkorn, K. and Wagner, S. and Pfeiffer, M. and Jin, L. and Khon, V. and Wang, Y. and Herzschuh, Ulrike}, title = {The evolution of sub-monsoon systems in the Afro-Asian monsoon region during the Holocene - comparison of different transient climate model simulations}, series = {Climate of the past : an interactive open access journal of the European Geosciences Union}, volume = {11}, journal = {Climate of the past : an interactive open access journal of the European Geosciences Union}, number = {2}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1814-9324}, doi = {10.5194/cp-11-305-2015}, pages = {305 -- 326}, year = {2015}, abstract = {The recently proposed global monsoon hypothesis interprets monsoon systems as part of one global-scale atmospheric overturning circulation, implying a connection between the regional monsoon systems and an in-phase behaviour of all northern hemispheric monsoons on annual timescales (Trenberth et al., 2000). Whether this concept can be applied to past climates and variability on longer timescales is still under debate, because the monsoon systems exhibit different regional characteristics such as different seasonality (i. e. onset, peak and withdrawal). To investigate the interconnection of different monsoon systems during the pre-industrial Holocene, five transient global climate model simulations have been analysed with respect to the rainfall trend and variability in different sub-domains of the Afro-Asian monsoon region. Our analysis suggests that on millennial timescales with varying orbital forcing, the monsoons do not behave as a tightly connected global system. According to the models, the Indian and North African monsoons are coupled, showing similar rainfall trend and moderate correlation in centennial rainfall variability in all models. The East Asian monsoon changes independently during the Holocene. The dissimilarities in the seasonality of the monsoon sub-systems lead to a stronger response of the North African and Indian monsoon systems to the Holocene insolation forcing than of the East Asian monsoon and affect the seasonal distribution of Holocene rainfall variations. Within the Indian and North African monsoon domain, precipitation solely changes during the summer months, showing a decreasing Holocene precipitation trend. In the East Asian monsoon region, the precipitation signal is determined by an increasing precipitation trend during spring and a decreasing precipitation change during summer, partly balancing each other. A synthesis of reconstructions and the model results do not reveal an impact of the different seasonality on the timing of the Holocene rainfall optimum in the different sub-monsoon systems. Rather they indicate locally inhomogeneous rainfall changes and show that single palaeo-records should not be used to characterise the rainfall change and monsoon evolution for entire monsoon sub-systems.}, language = {en} } @article{SiddiquiLuehrStolleetal.2015, author = {Siddiqui, Tarique Adnan and Luehr, H. and Stolle, Claudia and Park, J.}, title = {Relation between stratospheric sudden warming and the lunar effect on the equatorial electrojet based on Huancayo recordings}, series = {Annales geophysicae}, volume = {33}, journal = {Annales geophysicae}, number = {2}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {0992-7689}, doi = {10.5194/angeo-33-235-2015}, pages = {235 -- 243}, year = {2015}, abstract = {It has been known for many decades that the lunar tidal influence in the equatorial electrojet (EEJ) is noticeably enhanced during Northern Hemisphere winters. Recent literature has discussed the role of stratospheric sudden warming (SSW) events behind the enhancement of lunar tides and the findings suggest a positive correlation between the lunar tidal amplitude and lower stratospheric parameters (zonal mean air temperature and zonal mean zonal wind) during SSW events. The positive correlation raises the question whether an inverse approach could also be developed which makes it possible to deduce the occurrence of SSW events before their direct observations (before 1952) from the amplitude of the lunar tides. This study presents an analysis technique based on the phase of the semi-monthly lunar tide to determine the lunar tidal modulation of the EEJ. A statistical approach using the superposed epoch analysis is also carried out to formulate a relation between the EEJ tidal amplitude and lower stratospheric parameters. Using these results, we have estimated a threshold value for the tidal wave power that could be used to identify years with SSW events from magnetic field observations.}, language = {en} } @article{ClasonMairNienowetal.2015, author = {Clason, Caroline C. and Mair, D. W. F. and Nienow, P. W. and Bartholomew, I. D. and Sole, Andrew and Palmer, Steven and Schwanghart, Wolfgang}, title = {Modelling the transfer of supraglacial meltwater to the bed of Leverett Glacier, Southwest Greenland}, series = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, volume = {9}, journal = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, number = {1}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1994-0416}, doi = {10.5194/tc-9-123-2015}, pages = {123 -- 138}, year = {2015}, abstract = {Meltwater delivered to the bed of the Greenland Ice Sheet is a driver of variable ice-motion through changes in effective pressure and enhanced basal lubrication. Ice surface velocities have been shown to respond rapidly both to meltwater production at the surface and to drainage of supraglacial lakes, suggesting efficient transfer of meltwater from the supraglacial to subglacial hydrological systems. Although considerable effort is currently being directed towards improved modelling of the controlling surface and basal processes, modelling the temporal and spatial evolution of the transfer of melt to the bed has received less attention. Here we present the results of spatially distributed modelling for prediction of moulins and lake drainages on the Leverett Glacier in Southwest Greenland. The model is run for the 2009 and 2010 ablation seasons, and for future increased melt scenarios. The temporal pattern of modelled lake drainages are qualitatively comparable with those documented from analyses of repeat satellite imagery. The modelled timings and locations of delivery of meltwater to the bed also match well with observed temporal and spatial patterns of ice surface speed-ups. This is particularly true for the lower catchment (< 1000 m a.s.l.) where both the model and observations indicate that the development of moulins is the main mechanism for the transfer of surface meltwater to the bed. At higher elevations (e.g. 1250-1500 m a.s.l.) the development and drainage of supraglacial lakes becomes increasingly important. At these higher elevations, the delay between modelled melt generation and subsequent delivery of melt to the bed matches the observed delay between the peak air temperatures and subsequent velocity speed-ups, while the instantaneous transfer of melt to the bed in a control simulation does not. Although both moulins and lake drainages are predicted to increase in number for future warmer climate scenarios, the lake drainages play an increasingly important role in both expanding the area over which melt accesses the bed and in enabling a greater proportion of surface melt to reach the bed.}, language = {en} } @article{KormannFranckeBronstert2015, author = {Kormann, Christoph and Francke, Till and Bronstert, Axel}, title = {Detection of regional climate change effects on alpine hydrology by daily resolution trend analysis in Tyrol, Austria}, series = {Journal of water and climate change}, volume = {6}, journal = {Journal of water and climate change}, number = {1}, publisher = {IWA Publ.}, address = {London}, issn = {2040-2244}, doi = {10.2166/wcc.2014.099}, pages = {124 -- 143}, year = {2015}, abstract = {Owing to average temperature increases of at least twice the global mean, climate change is expected to have strong impacts on local hydrology and climatology in the Alps. Nevertheless, trend analyses of hydro-climatic station data rarely reveal clear patterns concerning climate change signals except in temperature observations. However, trend research has thus far mostly been based on analysing trends of averaged data such as yearly, seasonal or monthly averages and has therefore often not been able to detect the finer temporal dynamics. For this reason, we derived 30-day moving average trends, providing a daily resolution of the timing and magnitude of trends within the seasons. Results are validated by including different time periods. We studied daily observations of mean temperature, liquid and solid precipitation, snow height and runoff in the relatively dry central Alpine region in Tyrol, Austria. Our results indicate that the vast majority of changes are observed throughout spring to early summer, most likely triggered by the strong temperature increase during this season. Temperature, streamflow and snow trends have clearly amplified during recent decades. The overall results are consistent over the entire investigation area and different time periods.}, language = {en} } @article{HeistermannCollisDixonetal.2015, author = {Heistermann, Maik and Collis, Scott and Dixon, M. J. and Giangrande, S. and Helmus, J. J. and Kelley, B. and Koistinen, J. and Michelson, D. B. and Peura, M. and Pfaff, T. and Wolff, D. B.}, title = {The emergence of open-source software for the weather radar community}, series = {Bulletin of the American Meteorological Society}, volume = {96}, journal = {Bulletin of the American Meteorological Society}, number = {1}, publisher = {American Meteorological Soc.}, address = {Boston}, issn = {0003-0007}, doi = {10.1175/BAMS-D-13-00240.1}, pages = {117 -- +}, year = {2015}, abstract = {Weather radar analysis has become increasingly sophisticated over the past 50 years, and efforts to keep software up to date have generally lagged behind the needs of the users. We argue that progress has been impeded by the fact that software has not been developed and shared as a community. Recently, the situation has been changing. In this paper, the developers of a number of open-source software (OSS) projects highlight the potential of OSS to advance radar-related research. We argue that the community-based development of OSS holds the potential to reduce duplication of efforts and to create transparency in implemented algorithms while improving the quality and scope of the software. We also conclude that there is sufficiently mature technology to support collaboration across different software projects. This could allow for consolidation toward a set of interoperable software platforms, each designed to accommodate very specific user requirements.}, language = {en} } @article{RolinskiRammigWalzetal.2015, author = {Rolinski, Susanne and Rammig, A. and Walz, Ariane and von Bloh, Werner and van Oijen, M. and Thonicke, Kirsten}, title = {A probabilistic risk assessment for the vulnerability of the European carbon cycle to weather extremes: the ecosystem perspective}, series = {Biogeosciences}, volume = {12}, journal = {Biogeosciences}, number = {6}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1726-4170}, doi = {10.5194/bg-12-1813-2015}, pages = {1813 -- 1831}, year = {2015}, abstract = {Extreme weather events are likely to occur more often under climate change and the resulting effects on ecosystems could lead to a further acceleration of climate change. But not all extreme weather events lead to extreme ecosystem response. Here, we focus on hazardous ecosystem behaviour and identify coinciding weather conditions. We use a simple probabilistic risk assessment based on time series of ecosystem behaviour and climate conditions. Given the risk assessment terminology, vulnerability and risk for the previously defined hazard are estimated on the basis of observed hazardous ecosystem behaviour. We apply this approach to extreme responses of terrestrial ecosystems to drought, defining the hazard as a negative net biome productivity over a 12-month period. We show an application for two selected sites using data for 1981-2010 and then apply the method to the pan-European scale for the same period, based on numerical modelling results (LPJmL for ecosystem behaviour; ERA-Interim data for climate). Our site-specific results demonstrate the applicability of the proposed method, using the SPEI to describe the climate condition. The site in Spain provides an example of vulnerability to drought because the expected value of the SPEI is 0.4 lower for hazardous than for non-hazardous ecosystem behaviour. In northern Germany, on the contrary, the site is not vulnerable to drought because the SPEI expectation values imply wetter conditions in the hazard case than in the non-hazard case. At the pan-European scale, ecosystem vulnerability to drought is calculated in the Mediterranean and temperate region, whereas Scandinavian ecosystems are vulnerable under conditions without water shortages. These first model- based applications indicate the conceptual advantages of the proposed method by focusing on the identification of critical weather conditions for which we observe hazardous ecosystem behaviour in the analysed data set. Application of the method to empirical time series and to future climate would be important next steps to test the approach.}, language = {en} } @article{KienzlerPechKreibichetal.2015, author = {Kienzler, Sarah and Pech, Ina and Kreibich, Heidi and Mueller, M. and Thieken, Annegret}, title = {After the extreme flood in 2002: changes in preparedness, response and recovery of flood-affected residents in Germany between 2005 and 2011}, series = {Natural hazards and earth system sciences}, volume = {15}, journal = {Natural hazards and earth system sciences}, number = {3}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-15-505-2015}, pages = {505 -- 526}, year = {2015}, abstract = {After the flood in 2002, the level of private precautions taken increased considerably. One contributing factor is the fact that, in general, a larger proportion of people knew that they were at risk of flooding. The best level of precaution was found before the flood events in 2006 and 2011. The main reason for this might be that residents had more experience with flooding than residents affected in 2005 or 2010. Yet, overall, flood experience and knowledge did not necessarily result in building retrofitting or flood-proofing measures, which are considered as mitigating damages most effectively. Hence, investments still need to be stimulated in order to reduce future damage more efficiently.}, language = {en} } @article{KormannFranckeRenneretal.2015, author = {Kormann, Christoph and Francke, Till and Renner, M. and Bronstert, Axel}, title = {Attribution of high resolution streamflow trends in Western Austria - an approach based on climate and discharge station data}, series = {Hydrology and earth system sciences : HESS}, volume = {19}, journal = {Hydrology and earth system sciences : HESS}, number = {3}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-19-1225-2015}, pages = {1225 -- 1245}, year = {2015}, abstract = {The results of streamflow trend studies are often characterized by mostly insignificant trends and inexplicable spatial patterns. In our study region, Western Austria, this applies especially for trends of annually averaged runoff. However, analysing the altitudinal aspect, we found that there is a trend gradient from higher-altitude to lower-altitude stations, i.e. a pattern of mostly positive annual trends at higher stations and negative ones at lower stations. At mid-altitudes, the trends are mostly insignificant. Here we hypothesize that the streamflow trends are caused by the following two main processes: on the one hand, melting glaciers produce excess runoff at higher-altitude watersheds. On the other hand, rising temperatures potentially alter hydrological conditions in terms of less snowfall, higher infiltration, enhanced evapotranspiration, etc., which in turn results in decreasing streamflow trends at lower-altitude watersheds. However, these patterns are masked at mid-altitudes because the resulting positive and negative trends balance each other. To support these hypotheses, we attempted to attribute the detected trends to specific causes. For this purpose, we analysed trends of filtered daily streamflow data, as the causes for these changes might be restricted to a smaller temporal scale than the annual one. This allowed for the explicit determination of the exact days of year (DOYs) when certain streamflow trends emerge, which were then linked with the corresponding DOYs of the trends and characteristic dates of other observed variables, e.g. the average DOY when temperature crosses the freezing point in spring. Based on these analyses, an empirical statistical model was derived that was able to simulate daily streamflow trends sufficiently well. Analyses of subdaily streamflow changes provided additional insights. Finally, the present study supports many modelling approaches in the literature which found out that the main drivers of alpine streamflow changes are increased glacial melt, earlier snowmelt and lower snow accumulation in wintertime.}, language = {en} } @article{GuillemoteauSailhacBoulangeretal.2015, author = {Guillemoteau, Julien and Sailhac, Pascal and Boulanger, Charles and Trules, Jeremie}, title = {Inversion of ground constant offset loop-loop electromagnetic data for a large range of induction numbers}, series = {Geophysics}, volume = {80}, journal = {Geophysics}, number = {1}, publisher = {Society of Exploration Geophysicists}, address = {Tulsa}, issn = {0016-8033}, doi = {10.1190/GEO2014-0005.1}, pages = {E11 -- E21}, year = {2015}, abstract = {Ground loop-loop electromagnetic surveys are often conducted to fulfill the low-induction-number condition. To image the distribution of electric conductivity inside the ground, it is then necessary to collect a multioffset data set. We considered that less time-consuming constant offset measurements can also reach this objective. This can be achieved by performing multifrequency soundings, which are commonly performed for the airborne electromagnetic method. Ground multifrequency soundings have to be interpreted carefully because they contain high-induction-number data. These data are interpreted in two steps. First, the in-phase and out-of-phase data are converted into robust apparent conductivities valid for all the induction numbers. Second, the apparent conductivity data are inverted in 1D and 2D to obtain the true distribution of the ground conductivity. For the inversion, we used a general half-space Jacobian for the apparent conductivity valid for all the induction numbers. This method was applied and validated on synthetic data computed with the full Maxwell theory. The method was then applied on field data acquired in the test site of Provins, in the Parisian basin, France. The result revealed good agreement with borehole and geologic information, demonstrating the applicability of our method.}, language = {en} } @article{AichnerFeakinsLeeetal.2015, author = {Aichner, Bernhard and Feakins, Sarah J. and Lee, J. E. and Herzschuh, Ulrike and Liu, X.}, title = {High-resolution leaf wax carbon and hydrogen isotopic record of the late Holocene paleoclimate in arid Central Asia}, series = {Climate of the past : an interactive open access journal of the European Geosciences Union}, volume = {11}, journal = {Climate of the past : an interactive open access journal of the European Geosciences Union}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1814-9324}, doi = {10.5194/cp-11-619-2015}, pages = {619 -- 633}, year = {2015}, abstract = {Central Asia is located at the confluence of large-scale atmospheric circulation systems. It is thus likely to be highly susceptible to changes in the dynamics of those systems; however, little is still known about the regional paleoclimate history. Here we present carbon and hydrogen isotopic compositions of n-alkanoic acids from a late Holocene sediment core from Lake Karakuli (eastern Pamir, Xinjiang Province, China). Instrumental evidence and isotopeenabled climate model experiments with the Laboratoire de Meteorologie Dynamique Zoom model version 4 (LMDZ4) demonstrate that delta D values of precipitation in the region are influenced by both temperature and precipitation amount. We find that these parameters are inversely correlated on an annual scale, i.e., the climate has varied between relatively cool and wet and more warm and dry over the last 50 years. Since the isotopic signals of these changes are in the same direction and therefore additive, isotopes in precipitation are sensitive recorders of climatic changes in the region. Additionally, we infer that plants use year-round precipitation (including snowmelt), and thus leaf wax delta D values must also respond to shifts in the proportion of moisture derived from westerly storms during late winter and early spring. Downcore results give evidence for a gradual shift to cooler and wetter climates between 3.5 and 2.5 cal kyr BP, interrupted by a warm and dry episode between 3.0 and 2.7 kyr BP. Further cool and wet episodes occur between 1.9 and 1.5 and between 0.6 and 0.1 kyr BP, the latter coeval with the Little Ice Age. Warm and dry episodes from 2.5 to 1.9 and 1.5 to 0.6 kyr BP coincide with the Roman Warm Period and Medieval Climate Anomaly, respectively. Finally, we find a drying tend in recent decades. Regional comparisons lead us to infer that the strength and position of the westerlies, and wider northern hemispheric climate dynamics, control climatic shifts in arid Central Asia, leading to complex local responses. Our new archive from Lake Karakuli provides a detailed record of the local signatures of these climate transitions in the eastern Pamir.}, language = {en} } @article{StraussSchirrmeisterMangelsdorfetal.2015, author = {Strauss, Jens and Schirrmeister, Lutz and Mangelsdorf, Kai and Eichhorn, L. and Wetterich, Sebastian and Herzschuh, Ulrike}, title = {Organic-matter quality of deep permafrost carbon - a study from Arctic Siberia}, series = {Biogeosciences}, volume = {12}, journal = {Biogeosciences}, number = {7}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1726-4170}, doi = {10.5194/bg-12-2227-2015}, pages = {2227 -- 2245}, year = {2015}, abstract = {The organic-carbon (OC) pool accumulated in Arctic permafrost (perennially frozen ground) equals the carbon stored in the modern atmosphere. To give an idea of how Yedoma region permafrost could respond under future climatic warming, we conducted a study to quantify the organic-matter quality (here defined as the intrinsic potential to be further transformed, decomposed, and mineralized) of late Pleistocene (Yedoma) and Holocene (thermokarst) deposits on the Buor-Khaya Peninsula, northeast Siberia. The objective of this study was to develop a stratigraphic classified organic-matter quality characterization. For this purpose the degree of organic-matter decomposition was estimated by using a multiproxy approach. We applied sedimentological (grain-size analyses, bulk density, ice content) and geochemical parameters (total OC, stable carbon isotopes (delta C-13),total organic carbon : nitrogen (C / N) ratios) as well as lipid biomarkers (n-alkanes, n-fatty acids, hopanes, triterpenoids, and biomarker indices, i.e., average chain length, carbon preference index (CPI), and higher-plant fatty-acid index (HPFA)). Our results show that the Yedoma and thermokarst organic-matter qualities for further decomposition exhibit no obvious degradation-depth trend. Relatively, the C / N and delta C-13 values and the HPFA index show a significantly better preservation of the organic matter stored in thermokarst deposits compared to Yedoma deposits. The CPI data suggest less degradation of the organic matter from both deposits, with a higher value for Yedoma organic matter. As the interquartile ranges of the proxies mostly over-lap, we interpret this as indicating comparable quality for further decomposition for both kinds of deposits with likely better thermokarst organic-matter quality. Supported by principal component analyses, the sediment parameters and quality proxies of Yedoma and thermokarst deposits could not be unambiguously separated from each other. This revealed that the organic-matter vulnerability is heterogeneous and depends on different decomposition trajectories and the previous decomposition and preservation history. Elucidating this was one of the major new contributions of our multiproxy study. With the addition of biomarker data, it was possible to show that permafrost organic-matter degradation likely occurs via a combination of (uncompleted) degradation cycles or a cascade of degradation steps rather than as a linear function of age or sediment facies. We conclude that the amount of organic matter in the studied sediments is high for mineral soils and of good quality and therefore susceptible to future decomposition. The lack of depth trends shows that permafrost acts like a giant freezer, preserving the constant quality of ancient organic matter. When undecomposed Yedoma organic matter is mobilized via thermokarst processes, the fate of this carbon depends largely on the environmental conditions; the carbon could be preserved in an undecomposed state till refreezing occurs. If modern input has occurred, thermokarst organic matter could be of a better quality for future microbial decomposition than that found in Yedoma deposits.}, language = {en} } @article{SunyerHundechaLawrenceetal.2015, author = {Sunyer, M. A. and Hundecha, Y. and Lawrence, D. and Madsen, H. and Willems, Patrick and Martinkova, M. and Vormoor, Klaus Josef and B{\"u}rger, Gerd and Hanel, M. and Kriauciuniene, J. and Loukas, A. and Osuch, M. and Yucel, I.}, title = {Inter-comparison of statistical downscaling methods for projection of extreme precipitation in Europe}, series = {Hydrology and earth system sciences : HESS}, volume = {19}, journal = {Hydrology and earth system sciences : HESS}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-19-1827-2015}, pages = {1827 -- 1847}, year = {2015}, abstract = {Information on extreme precipitation for future climate is needed to assess the changes in the frequency and intensity of flooding. The primary source of information in climate change impact studies is climate model projections. However, due to the coarse resolution and biases of these models, they cannot be directly used in hydrological models. Hence, statistical downscaling is necessary to address climate change impacts at the catchment scale. This study compares eight statistical downscaling methods (SDMs) often used in climate change impact studies. Four methods are based on change factors (CFs), three are bias correction (BC) methods, and one is a perfect prognosis method. The eight methods are used to downscale precipitation output from 15 regional climate models (RCMs) from the ENSEMBLES project for 11 catchments in Europe. The overall results point to an increase in extreme precipitation in most catchments in both winter and summer. For individual catchments, the downscaled time series tend to agree on the direction of the change but differ in the magnitude. Differences between the SDMs vary between the catchments and depend on the season analysed. Similarly, general conclusions cannot be drawn regarding the differences between CFs and BC methods. The performance of the BC methods during the control period also depends on the catchment, but in most cases they represent an improvement compared to RCM outputs. Analysis of the variance in the ensemble of RCMs and SDMs indicates that at least 30\% and up to approximately half of the total variance is derived from the SDMs. This study illustrates the large variability in the expected changes in extreme precipitation and highlights the need for considering an ensemble of both SDMs and climate models. Recommendations are provided for the selection of the most suitable SDMs to include in the analysis.}, language = {en} } @article{PrahlRybskiBurghoffetal.2015, author = {Prahl, Boris F. and Rybski, Diego and Burghoff, Olaf and Kropp, J{\"u}rgen}, title = {Comparison of storm damage functions and their performance}, series = {Natural hazards and earth system sciences}, volume = {15}, journal = {Natural hazards and earth system sciences}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-15-769-2015}, pages = {769 -- 788}, year = {2015}, abstract = {Winter storms are the most costly natural hazard for European residential property. We compare four distinct storm damage functions with respect to their forecast accuracy and variability, with particular regard to the most severe winter storms. The analysis focuses on daily loss estimates under differing spatial aggregation, ranging from district to country level. We discuss the broad and heavily skewed distribution of insured losses posing difficulties for both the calibration and the evaluation of damage functions. From theoretical considerations, we provide a synthesis between the frequently discussed cubic wind-damage relationship and recent studies that report much steeper damage functions for European winter storms. The performance of the storm loss models is evaluated for two sources of wind gust data, direct observations by the German Weather Service and ERA-Interim reanalysis data. While the choice of gust data has little impact on the evaluation of German storm loss, spatially resolved coefficients of variation reveal dependence between model and data choice. The comparison shows that the probabilistic models by Heneka et al. (2006) and Prahl et al. (2012) both provide accurate loss predictions for moderate to extreme losses, with generally small coefficients of variation. We favour the latter model in terms of model applicability. Application of the versatile deterministic model by Klawa and Ulbrich (2003) should be restricted to extreme loss, for which it shows the least bias and errors comparable to the probabilistic model by Prahl et al. (2012).}, language = {en} } @article{MarcHovius2015, author = {Marc, Odin and Hovius, Niels}, title = {Amalgamation in landslide maps}, series = {Natural hazards and earth system sciences}, volume = {15}, journal = {Natural hazards and earth system sciences}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-15-723-2015}, pages = {723 -- 733}, year = {2015}, abstract = {Inventories of individually delineated landslides are a key to understanding landslide physics and mitigating their impact. They permit assessment of area-frequency distributions and landslide volumes, and testing of statistical correlations between landslides and physical parameters such as topographic gradient or seismic strong motion. Amalgamation, i.e. the mapping of several adjacent landslides as a single polygon, can lead to potentially severe distortion of the statistics of these inventories. This problem can be especially severe in data sets produced by automated mapping. We present five inventories of earthquake-induced landslides mapped with different materials and techniques and affected by varying degrees of amalgamation. Errors on the total landslide volume and power-law exponent of the area-frequency distribution, resulting from amalgamation, may be up to 200 and 50 \%, respectively. We present an algorithm based on image and digital elevation model (DEM) analysis, for automatic identification of amalgamated polygons. On a set of about 2000 polygons larger than 1000 m(2), tracing landslides triggered by the 1994 Northridge earthquake, the algorithm performs well, with only 2.7-3.6\% incorrectly amalgamated landslides missed and 3.9-4.8\% correct polygons incorrectly identified as amalgams. This algorithm can be used broadly to check landslide inventories and allow faster correction by automating the identification of amalgamation.}, language = {en} } @article{FritzOpelTanskietal.2015, author = {Fritz, Michael and Opel, Thomas and Tanski, George and Herzschuh, Ulrike and Meyer, H. and Eulenburg, A. and Lantuit, Hugues}, title = {Dissolved organic carbon (DOC) in Arctic ground ice}, series = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, volume = {9}, journal = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, number = {2}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1994-0416}, doi = {10.5194/tc-9-737-2015}, pages = {737 -- 752}, year = {2015}, abstract = {Thermal permafrost degradation and coastal erosion in the Arctic remobilize substantial amounts of organic carbon (OC) and nutrients which have accumulated in late Pleistocene and Holocene unconsolidated deposits. Permafrost vulnerability to thaw subsidence, collapsing coastlines and irreversible landscape change are largely due to the presence of large amounts of massive ground ice such as ice wedges. However, ground ice has not, until now, been considered to be a source of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and other elements which are important for ecosystems and carbon cycling. Here we show, using biogeochemical data from a large number of different ice bodies throughout the Arctic, that ice wedges have the greatest potential for DOC storage, with a maximum of 28.6 mg L-1 (mean: 9.6 mg L-1). Variation in DOC concentration is positively correlated with and explained by the concentrations and relative amounts of typically terrestrial cations such as Mg2+ and K+. DOC sequestration into ground ice was more effective during the late Pleistocene than during the Holocene, which can be explained by rapid sediment and OC accumulation, the prevalence of more easily degradable vegetation and immediate incorporation into permafrost. We assume that pristine snowmelt is able to leach considerable amounts of well-preserved and highly bioavailable DOC as well as other elements from surface sediments, which are rapidly frozen and stored in ground ice, especially in ice wedges, even before further degradation. We found that ice wedges in the Yedoma region represent a significant DOC (45.2 Tg) and DIC (33.6 Tg) pool in permafrost areas and a freshwater reservoir of 4200 km(2). This study underlines the need to discriminate between particulate OC and DOC to assess the availability and vulnerability of the permafrost car-bon pool for ecosystems and climate feedback upon mobilization.}, language = {en} } @article{MeyerSchwanghartKorupetal.2015, author = {Meyer, Nele Kristin and Schwanghart, Wolfgang and Korup, Oliver and Nadim, F.}, title = {Roads at risk}, series = {Natural hazards and earth system sciences}, volume = {15}, journal = {Natural hazards and earth system sciences}, number = {5}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-15-985-2015}, pages = {985 -- 995}, year = {2015}, abstract = {Globalisation and interregional exchange of people, goods, and services has boosted the importance of and reliance on all kinds of transport networks. The linear structure of road networks is especially sensitive to natural hazards. In southern Norway, steep topography and extreme weather events promote frequent traffic disruption caused by debris flows. Topographic susceptibility and trigger frequency maps serve as input into a hazard appraisal at the scale of first-order catchments to quantify the impact of debris flows on the road network in terms of a failure likelihood of each link connecting two network vertices, e.g. road junctions. We compute total additional traffic loads as a function of traffic volume and excess distance, i.e. the extra length of an alternative path connecting two previously disrupted network vertices using a shortest-path algorithm. Our risk metric of link failure is the total additional annual traffic load, expressed as vehicle kilometres, because of debris-flow-related road closures. We present two scenarios demonstrating the impact of debris flows on the road network and quantify the associated path-failure likelihood between major cities in southern Norway. The scenarios indicate that major routes crossing the central and north-western part of the study area are associated with high link-failure risk. Yet options for detours on major routes are manifold and incur only little additional costs provided that drivers are sufficiently well informed about road closures. Our risk estimates may be of importance to road network managers and transport companies relying on speedy delivery of services and goods.}, language = {en} } @article{PohlHoffmannHagemannetal.2015, author = {Pohl, M. and Hoffmann, M. and Hagemann, U. and Giebels, M. and Borraz, Elisa Albiac and Sommer, Michael and Augustin, J{\"u}rgen}, title = {Dynamic C and N stocks - key factors controlling the C gas exchange of maize in heterogenous peatland}, series = {Biogeosciences}, volume = {12}, journal = {Biogeosciences}, number = {9}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1726-4170}, doi = {10.5194/bg-12-2737-2015}, pages = {2737 -- 2752}, year = {2015}, abstract = {The drainage and cultivation of fen peatlands create complex small-scale mosaics of soils with extremely variable soil organic carbon (SOC) stocks and groundwater levels (GWLs). To date, the significance of such sites as sources or sinks for greenhouse gases such as CO2 and CH4 is still unclear, especially if the sites are used for cropland. As individual control factors such as GWL fail to account for this complexity, holistic approaches combining gas fluxes with the underlying processes are required to understand the carbon (C) gas exchange of drained fens. It can be assumed that the stocks of SOC and N located above the variable GWL - defined as dynamic C and N stocks - play a key role in the regulation of the plant- and microbially mediated CO2 fluxes in these soils and, inversely, for CH4. To test this assumption, the present study analysed the C gas exchange (gross primary production - GPP; ecosystem respiration - R-eco; net ecosystem exchange - NEE; CH4) of maize using manual chambers for 4 years. The study sites were located near Paulinenaue, Germany, where we selected three soil types representing the full gradient of GWL and SOC stocks (0-1 m) of the landscape: (a) Haplic Arenosol (AR; 8 kg C m(-2)); (b) Mollic Gleysol (GL; 38 kg C m(-2)); and (c) Hemic Histosol (HS; 87 kg C m(-2)). Daily GWL data were used to calculate dynamic SOC (SOCdyn) and N (N-dyn) stocks. Average annual NEE differed considerably among sites, ranging from 47 +/- 30 g C m(-2) yr(-1) in AR to -305 +/- 123 g C m(-2) yr(-1) in GL and -127 +/- 212 g C m(-2) yr(-1) in HS. While static SOC and N stocks showed no significant effect on C fluxes, SOCdyn and N-dyn and their interaction with GWL strongly influenced the C gas exchange, particularly NEE and the GPP : R-eco ratio. Moreover, based on nonlinear regression analysis, 86\% of NEE variability was explained by GWL and SOCdyn. The observed high relevance of dynamic SOC and N stocks in the aerobic zone for plant and soil gas exchange likely originates from the effects of GWL-dependent N availability on C formation and transformation processes in the plant-soil system, which promote CO2 input via GPP more than CO2 emission via R-eco. The process-oriented approach of dynamic C and N stocks is a promising, potentially generalisable method for system-oriented investigations of the C gas exchange of groundwater-influenced soils and could be expanded to other nutrients and soil characteristics. However, in order to assess the climate impact of arable sites on drained peatlands, it is always necessary to consider the entire range of groundwater-influenced mineral and organic soils and their respective areal extent within the soil landscape.}, language = {en} } @article{AyguelOkayOberhaenslietal.2015, author = {Ayg{\"u}l, Mesut and Okay, Aral I. and Oberh{\"a}nsli, Roland and Ziemann, Martin Andreas}, title = {Thermal structure of low-grade accreted Lower Cretaceous distal turbidites, the Central Pontides, Turkey: insights for tectonic thickening of an accretionary wedge}, series = {Turkish journal of earth sciences = T{\"u}rk yerbilimleri dergisi}, volume = {24}, journal = {Turkish journal of earth sciences = T{\"u}rk yerbilimleri dergisi}, number = {5}, publisher = {T{\"u}bitak}, address = {Ankara}, issn = {1300-0985}, doi = {10.3906/yer-1504-4}, pages = {461 -- 474}, year = {2015}, abstract = {Albian-Turonian subduction-accretionary complexes are exposed widely in the Central Pontides. A major portion of the accretionary complexes is made up of a metaflysch sequence consisting of slate/phyllite and metasandstone intercalation with blocks of marble, Na-amphibole bearing metabasite, and serpentinite. The metaflysch sequence represents distal parts of a large Lower Cretaceous submarine turbidite fan deposited on the Laurasian active continental margin that was subsequently accreted and metamorphosed during the Albian. Raman spectra of carbonaceous material of the metapelitic rocks revealed that the metaflysch consists of metamorphic packets with distinct peak metamorphic temperatures. The majority of the metapelites are low-temperature (ca. 330 degrees C) slates characterized by lack of differentiation of the graphite (G) and D2 defect bands. They possibly represent offscraped distal turbidites along the toe of the Albian accretionary wedge. Other phyllites are characterized by a slightly pronounced G band with a D2 defect band occurring on its shoulder. Peak metamorphic temperatures of these phyllites are constrained to 370-385 degrees C. The phyllites are associated with a strip of incipient blueschist facies metabasites and are found as a sliver within the offscraped distal turbidites. We interpret the phyllites as underplated continental sediments together with oceanic crustal basalt along the basal decollement. Tectonic emplacement of the underplated rocks into the offscraped distal turbidites was possibly achieved by out-of-sequence thrusting causing tectonic thickening and uplift of the wedge.}, language = {en} } @article{ParkLuehrStolleetal.2015, author = {Park, J. and Luehr, H. and Stolle, Claudia and Malhotra, G. and Baker, J. B. H. and Buchert, Stephan and Gill, R.}, title = {Estimating along-track plasma drift speed from electron density measurements by the three Swarm satellites}, series = {Annales geophysicae}, volume = {33}, journal = {Annales geophysicae}, number = {7}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {0992-7689}, doi = {10.5194/angeo-33-829-2015}, pages = {829 -- 835}, year = {2015}, abstract = {Plasma convection in the high-latitude ionosphere provides important information about magnetosphere-ionosphere-thermosphere coupling. In this study we estimate the along-track component of plasma convection within and around the polar cap, using electron density profiles measured by the three Swarm satellites. The velocity values estimated from the two different satellite pairs agree with each other. In both hemispheres the estimated velocity is generally anti-sunward, especially for higher speeds. The obtained velocity is in qualitative agreement with Super Dual Auroral Radar Network data. Our method can supplement currently available instruments for ionospheric plasma velocity measurements, especially in cases where these traditional instruments suffer from their inherent limitations. Also, the method can be generalized to other satellite constellations carrying electron density probes.}, language = {en} } @article{MotuzaSliaupaTimmerman2015, author = {Motuza, Gediminas and Sliaupa, Saulius and Timmerman, Martin Jan}, title = {Geochemistry and Ar-40/Ar-39 age of Early Carboniferous dolerite sills in the southern Baltic Sea}, series = {Estonian journal of earth sciences}, volume = {64}, journal = {Estonian journal of earth sciences}, number = {3}, publisher = {Estonian Academy Publ.}, address = {Tallinn}, issn = {1736-4728}, doi = {10.3176/earth.2015.30}, pages = {233 -- 248}, year = {2015}, abstract = {The Early Carboniferous magmatic event in the southern Baltic Sea is manifested by dolerite intrusions. The presumable area in which the dolerite intrusions occur ranges from 30 to 60 km in east-west direction, and is about 100 km in north-south direction. The dolerites were sampled in well D1-1 and investigated by applying chemical analysis and Ar-40/Ar-39 step-heating dating. Dolerites are classified as alkali and sodic, characterized by high TiO2 (3.92, 3.99 wt\%) and P2O5 (1.67, 1.77 wt\%) and low MgO (4.89, 4.91 wt\%) concentrations, enriched in light rare earth elements, originated from an enriched mantle magma source and emplaced in a continental rift tectonic setting. The 351 +/- 11 Ma Ar-40/Ar-39 plateau age for groundmass plagioclase indicates a considerable age gap with the 310-250 Ma magmatism in southern Scandinavia and northern Germany. The magmatic rocks in the Baltic Sedimentary Basin are coeval with alkaline intrusions of NE Poland. Both magmatic provinces lie in the northwestward prolongation of the Pripyat-Dnieper-Donetsk Rift (370-359 Ma) and may constitute a later phase of magmatic activity of this propagating rift system.}, language = {en} } @article{FritzDeshpandeBouchardetal.2015, author = {Fritz, M. and Deshpande, B. N. and Bouchard, F. and Hogstrom, E. and Malenfant-Lepage, J. and Morgenstern, Anne and Nieuwendam, A. and Oliva, M. and Paquette, M. and Rudy, A. C. A. and Siewert, M. B. and Sjoberg, Y. and Weege, Stefanie}, title = {Brief Communication: Future avenues for permafrost science from the perspective of early career researchers}, series = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, volume = {9}, journal = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1994-0416}, doi = {10.5194/tc-9-1715-2015}, pages = {1715 -- 1720}, year = {2015}, abstract = {Accelerating climate change and increased economic and environmental interests in permafrost-affected regions have resulted in an acute need for more directed permafrost research. In June 2014, 88 early career researchers convened to identify future priorities for permafrost research. This multidisciplinary forum concluded that five research topics deserve greatest attention: permafrost landscape dynamics, permafrost thermal modeling, integration of traditional knowledge, spatial distribution of ground ice, and engineering issues. These topics underline the need for integrated research across a spectrum of permafrost-related domains and constitute a contribution to the Third International Conference on Arctic Research Planning (ICARP III).}, language = {en} } @article{SmithBookhagenCannon2015, author = {Smith, Taylor and Bookhagen, Bodo and Cannon, Forest}, title = {Improving semi-automated glacier mapping with a multi-method approach: applications in central Asia}, series = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, volume = {9}, journal = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, number = {5}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1994-0416}, doi = {10.5194/tc-9-1747-2015}, pages = {1747 -- 1759}, year = {2015}, abstract = {Studies of glaciers generally require precise glacier outlines. Where these are not available, extensive manual digitization in a geographic information system (GIS) must be performed, as current algorithms struggle to delineate glacier areas with debris cover or other irregular spectral profiles. Although several approaches have improved upon spectral band ratio delineation of glacier areas, none have entered wide use due to complexity or computational intensity. In this study, we present and apply a glacier mapping algorithm in Central Asia which delineates both clean glacier ice and debris-covered glacier tongues. The algorithm is built around the unique velocity and topographic characteristics of glaciers and further leverages spectral and spatial relationship data. We found that the algorithm misclassifies between 2 and 10\% of glacier areas, as compared to a similar to 750 glacier control data set, and can reliably classify a given Landsat scene in 3-5 min. The algorithm does not completely solve the difficulties inherent in classifying glacier areas from remotely sensed imagery but does represent a significant improvement over purely spectral-based classification schemes, such as the band ratio of Landsat 7 bands three and five or the normalized difference snow index. The main caveats of the algorithm are (1) classification errors at an individual glacier level, (2) reliance on manual intervention to separate connected glacier areas, and (3) dependence on fidelity of the input Landsat data.}, language = {en} } @article{EgholmAndersenKnudsenetal.2015, author = {Egholm, D. L. and Andersen, Jane Lund and Knudsen, M. F. and Jansen, John D. and Nielsen, S. B.}, title = {The periglacial engine of mountain erosion - Part 2: Modelling large-scale landscape evolution}, series = {Earth surface dynamics}, volume = {3}, journal = {Earth surface dynamics}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {2196-6311}, doi = {10.5194/esurf-3-463-2015}, pages = {463 -- 482}, year = {2015}, abstract = {There is growing recognition of strong periglacial control on bedrock erosion in mountain landscapes, including the shaping of low-relief surfaces at high elevations (summit flats). But, as yet, the hypothesis that frost action was crucial to the assumed Late Cenozoic rise in erosion rates remains compelling and untested. Here we present a landscape evolution model incorporating two key periglacial processes - regolith production via frost cracking and sediment transport via frost creep - which together are harnessed to variations in temperature and the evolving thickness of sediment cover. Our computational experiments time-integrate the contribution of frost action to shaping mountain topography over million-year timescales, with the primary and highly reproducible outcome being the development of flattish or gently convex summit flats. A simple scaling of temperature to marine delta O-18 records spanning the past 14 Myr indicates that the highest summit flats in mid-to high-latitude mountains may have formed via frost action prior to the Quaternary. We suggest that deep cooling in the Quaternary accelerated mechanical weathering globally by significantly expanding the area subject to frost. Further, the inclusion of subglacial erosion alongside periglacial processes in our computational experiments points to alpine glaciers increasing the long-term efficiency of frost-driven erosion by steepening hillslopes.}, language = {en} } @article{AndersenEgholmKnudsenetal.2015, author = {Andersen, Jane Lund and Egholm, D. L. and Knudsen, M. F. and Jansen, John D. and Nielsen, S. B.}, title = {The periglacial engine of mountain erosion - Part 1: Rates of frost cracking and frost creep}, series = {Earth surface dynamics}, volume = {3}, journal = {Earth surface dynamics}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {2196-6311}, doi = {10.5194/esurf-3-447-2015}, pages = {447 -- 462}, year = {2015}, abstract = {With accelerating climate cooling in the late Cenozoic, glacial and periglacial erosion became more widespread on the surface of the Earth. The resultant shift in erosion patterns significantly changed the large-scale morphology of many mountain ranges worldwide. Whereas the glacial fingerprint is easily distinguished by its characteristic fjords and U-shaped valleys, the periglacial fingerprint is more subtle but potentially prevails in some mid- to high-latitude landscapes. Previous models have advocated a frost-driven control on debris production at steep headwalls and glacial valley sides. Here we investigate the important role that periglacial processes also play in less steep parts of mountain landscapes. Understanding the influences of frost-driven processes in low-relief areas requires a focus on the consequences of an accreting soil mantle, which characterises such surfaces. We present a new model that quantifies two key physical processes: frost cracking and frost creep, as a function of both temperature and sediment thickness. Our results yield new insights into how climate and sediment transport properties combine to scale the intensity of periglacial processes. The thickness of the soil mantle strongly modulates the relation between climate and the intensity of mechanical weathering and sediment flux. Our results also point to an offset between the conditions that promote frost cracking and those that promote frost creep, indicating that a stable climate can provide optimal conditions for only one of those processes at a time. Finally, quantifying these relations also opens up the possibility of including periglacial processes in large-scale, long-term landscape evolution models, as demonstrated in a companion paper.}, language = {en} } @article{KellermannSchoebelKundelaetal.2015, author = {Kellermann, Patric and Schoebel, A. and Kundela, G. and Thieken, Annegret}, title = {Estimating flood damage to railway infrastructure - the case study of the March River flood in 2006 at the Austrian Northern Railway}, series = {Natural hazards and earth system sciences}, volume = {15}, journal = {Natural hazards and earth system sciences}, number = {11}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1561-8633}, doi = {10.5194/nhess-15-2485-2015}, pages = {2485 -- 2496}, year = {2015}, abstract = {Models for estimating flood losses to infrastructure are rare and their reliability is seldom investigated although infrastructure losses might contribute considerably to the overall flood losses. In this paper, an empirical modelling approach for estimating direct structural flood damage to railway infrastructure and associated financial losses is presented. Via a combination of event data, i.e. photo-documented damage on the Northern Railway in Lower Austria caused by the March River flood in 2006, and simulated flood characteristics, i.e. water levels, flow velocities and combinations thereof, the correlations between physical flood impact parameters and damage occurred to the railway track were investigated and subsequently rendered into a damage model. After calibrating the loss estimation using recorded repair costs of the Austrian Federal Railways, the model was applied to three synthetic scenarios with return periods of 30, 100 and 300 years of March River flooding. Finally, the model results are compared to depth-damage-curve-based approaches for the infrastructure sector obtained from the Rhine Atlas damage model and the Damage Scanner model. The results of this case study indicate a good performance of our two-stage model approach. However, due to a lack of independent event and damage data, the model could not yet be validated. Future research in natural risk should focus on the development of event and damage documentation procedures to overcome this significant hurdle in flood damage modelling.}, language = {en} } @article{WiggeringSteinhardt2015, author = {Wiggering, Hubert and Steinhardt, Uta}, title = {A conceptual model for site-specific agricultural land-use}, series = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog}, volume = {295}, journal = {Ecological modelling : international journal on ecological modelling and engineering and systems ecolog}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0304-3800}, doi = {10.1016/j.ecolmodel.2014.08.011}, pages = {42 -- 46}, year = {2015}, abstract = {Land-use concepts provide decision support for the most efficient usage options according to sustainable development and multifunctionality requirements. However, developments in landscape-related, agricultural production schemes are primarily driven by economic benefits. Therefore, most agricultural land-use concepts tackle particular problems or interests and lack a systemic perspective. As a result, we discuss a conceptual model for future site-specific agricultural land-use with an inbuilt requirement for adequate experimental sites to enable monitoring systems for a new generation of ecosystem models and for new approaches to address science-stakeholder interactions.}, language = {en} } @article{RudolphMohrGottfriedLamshoeftetal.2015, author = {Rudolph-Mohr, Nicole and Gottfried, Sebastian and Lamsh{\"o}ft, Marc and Z{\"u}hlke, Sebastian and Oswald, Sascha and Spiteller, Michael}, title = {Non-invasive imaging techniques to study O-2 micro-patterns around pesticide treated lupine roots}, series = {Geoderma : an international journal of soil science}, volume = {239}, journal = {Geoderma : an international journal of soil science}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0016-7061}, doi = {10.1016/j.geoderma.2014.10.022}, pages = {257 -- 264}, year = {2015}, abstract = {The soil root interface is a highly heterogeneous system, e.g. in terms of O-2 and pH distribution. The destructive character of conventional methods disturbs the natural conditions of those biogeochemical gradients. Therefore, experiments aiming to control these influences and study pesticide kinetics under given O-2 and pH conditions suffer from a large uncertainty of the "real" O-2/pH at a certain position. Our approach with two different imaging techniques will examine the soil-root interface as well as the dissipation of the applied pesticide at a high spatial resolution. The obtained outcomes show directly that the pH has an influence on enantioselective dissipation of the acetanilide fungicide metalaxyl. In areas with high pH from an applied racemic mixture, the R-enantiomer dissipates faster than the S-enantiomer. Moreover, we found significantly reduced oxygen values in the bulk soil and vicinity of metalaxyl treated roots compared to control plant roots. The combination of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) and fluorescence imaging indicated the oxygen-dependent behavior of metalaxyl at the root surface. The results presented here underline the great potential of combining different imaging methods to examine the soil-root interfaces as well as the dissipation of organic pollutants in small soil compartments. (C) 2014 Elsevier B.V. All rights reserved.}, language = {en} } @article{ThomasLischeidSteidletal.2015, author = {Thomas, Bj{\"o}rn and Lischeid, Gunnar and Steidl, J{\"o}rg and Dietrich, Ottfried}, title = {Long term shift of low flows predictors in small lowland catchments of Northeast Germany}, series = {Journal of hydrology}, volume = {521}, journal = {Journal of hydrology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2014.12.022}, pages = {508 -- 519}, year = {2015}, abstract = {Runoff, especially during summer months, and low flows have decreased in Central and Eastern Europe during the last decades. A detailed knowledge on predictors and dependencies between meteorological forcing, catchment properties and low flow is necessary to optimize regional adaption strategies to sustain minimum runoff. The objective of this study is to identify low flow predictors for 16 small catchments in Northeast Germany and their long-term shifts between 1965 and 2006. Non-linear regression models (support vector machine regression) were calibrated to iteratively select the most powerful low flow predictors regarding annual 30-day minimum flow (AM(30)). The data set consists of standardized precipitation (SPI) and potential evapotranspiration (SpETI) indices on different time scales and lag times. The potential evapotranspiration of the previous 48 and 3 months, as well as the precipitation of the previous 3 months and last year were the most relevant predictors for AM(30). Pearson correlation (r(2)) of the final model is 0.49 and if for every year the results for all catchments are averaged r(2) increases to 0.80 because extremes are smoothing out. Evapotranspiration was the most important low flow predictor for the study period. However, distinct long-term shifts in the predictive power of variables became apparent. The potential evapotranspiration of the previous 48 months explained most of the variance, but its relevance decreased during the last decades. The importance of precipitation variables increased with time. Model performance was higher at catchments with a more damped discharge behavior. The results indicate changes in the relevant processes or flow paths generating low flows. The identified predictors, temporal patterns and patterns between catchments will support the development of low flow monitoring systems and determine those catchments where adaption measures should aim more at increasing groundwater recharge. (C) 2014 Elsevier B.V. All rights reserved.}, language = {en} } @article{delFresnoDominguezCerdenaCescaetal.2015, author = {del Fresno, Carmen and Dominguez Cerdena, Itahiza and Cesca, Simone and Buforn, Elisa}, title = {The 8 October 2011 Earthquake at El Hierro (M-w 4.0): Focal Mechanisms of the Mainshock and Its Foreshocks}, series = {Bulletin of the Seismological Society of America}, volume = {105}, journal = {Bulletin of the Seismological Society of America}, number = {1}, publisher = {Seismological Society of America}, address = {Albany}, issn = {0037-1106}, doi = {10.1785/0120140151}, pages = {330 -- 340}, year = {2015}, abstract = {We have studied the focal mechanism of an M-w 4.0 earthquake that occurred on 8 October 2011 in the southwest of El Hierro (Canary Islands), the largest shock of the swarm that preceded the submarine eruption of El Hierro 2011-2012. The joint focal mechanism solution of 34 foreshocks has also been obtained. The results for the mainshock are consistent with a pure double-couple mechanism of a strike-slip motion with a reverse component and a focal depth of 12-13 km. The stress pattern obtained from the focal mechanism indicates horizontal compression in a north-northwest-south-southeast direction, parallel to the southern ridge of the island, and a quasi-horizontal extension in an east-west direction. Similar stress pattern is derived from the joint solution of the foreshocks. The occurrence of this family of earthquakes at the moment of the maximum strain rate of the pre-eruptive swarm suggests that their rupture process is related to tectonic stress, which led to the eruption only two days later, 5 km away from the mainshock epicenter.}, language = {en} } @article{BoersBookhagenMarengoetal.2015, author = {Boers, Niklas and Bookhagen, Bodo and Marengo, Jose and Marwan, Norbert and von Storch, Jin-Song and Kurths, J{\"u}rgen}, title = {Extreme Rainfall of the South American Monsoon System: A Dataset Comparison Using Complex Networks}, series = {Journal of climate}, volume = {28}, journal = {Journal of climate}, number = {3}, publisher = {American Meteorological Soc.}, address = {Boston}, issn = {0894-8755}, doi = {10.1175/JCLI-D-14-00340.1}, pages = {1031 -- 1056}, year = {2015}, abstract = {In this study, the authors compare six different rainfall datasets for South America with a focus on their representation of extreme rainfall during the monsoon season (December February): the gauge-calibrated TRMM 3B42 V7 satellite product; the near-real-time TRMM 3B42 V7 RT, the GPCP 1 degrees daily (1DD) V1.2 satellite gauge combination product, the Interim ECMWF Re-Analysis (ERA-Interim) product; output of a high-spatial-resolution run of the ECHAM6 global circulation model; and output of the regional climate model Eta. For the latter three, this study can be understood as a model evaluation. In addition to statistical values of local rainfall distributions, the authors focus on the spatial characteristics of extreme rainfall covariability. Since traditional approaches based on principal component analysis are not applicable in the context of extreme events, they apply and further develop methods based on complex network theory. This way, the authors uncover substantial differences in extreme rainfall patterns between the different datasets: (i) The three model-derived datasets yield very different results than the satellite gauge combinations regarding the main climatological propagation pathways of extreme events as well as the main convergence zones of the monsoon system. (ii) Large discrepancies are found for the development of mesoscale convective systems in southeastern South America. (iii) Both TRMM datasets and ECHAM6 indicate a linkage of extreme rainfall events between the central Amazon basin and the eastern slopes of the central Andes, but this pattern is not reproduced by the remaining datasets. The authors' study suggests that none of the three model-derived datasets adequately captures extreme rainfall patterns in South America.}, language = {en} } @article{HaendelvonSpechtKuehnetal.2015, author = {H{\"a}ndel, Annabel and von Specht, Sebastian and Kuehn, Nicolas M. and Scherbaum, Frank}, title = {Mixtures of ground-motion prediction equations as backbone models for a logic tree: an application to the subduction zone in Northern Chile}, series = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering}, volume = {13}, 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/s10518-014-9636-7}, pages = {483 -- 501}, year = {2015}, abstract = {In probabilistic seismic hazard analysis, different ground-motion prediction equations (GMPEs) are commonly combined within a logic tree framework. The selection of appropriate GMPEs, however, is a non-trivial task, especially for regions where strong motion data are sparse and where no indigenous GMPE exists because the set of models needs to capture the whole range of ground-motion uncertainty. In this study we investigate the aggregation of GMPEs into a mixture model with the aim to infer a backbone model that is able to represent the center of the ground-motion distribution in a logic tree analysis. This central model can be scaled up and down to obtain the full range of ground-motion uncertainty. The combination of models into a mixture is inferred from observed ground-motion data. We tested the new approach for Northern Chile, a region for which no indigenous GMPE exists. Mixture models were calculated for interface and intraslab type events individually. For each source type we aggregated eight subduction zone GMPEs using mainly new strong-motion data that were recorded within the Plate Boundary Observatory Chile project and that were processed within this study. We can show that the mixture performs better than any of its component GMPEs, and that it performs comparable to a regression model that was derived for the same dataset. The mixture model seems to represent the median ground motions in that region fairly well. It is thus able to serve as a backbone model for the logic tree.}, language = {en} } @article{WeberWicksLeStunffetal.2015, author = {Weber, Michael H. and Wicks, Charles and Le Stunff, Yves and Romanowicz, Barbara and Kr{\"u}ger, Frank}, title = {Seismic evidence for a steeply dipping reflector-stagnant slab in the mantle transition zone}, series = {Geophysical journal international}, volume = {200}, journal = {Geophysical journal international}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0956-540X}, doi = {10.1093/gji/ggu438}, pages = {1235 -- 1251}, year = {2015}, abstract = {Studies of seismic tomography have been highly successful at imaging the deep structure of subduction zones. In a study complementary to these tomographic studies, we use array seismology and reflected waves to image a stagnant slab in the mantle transition zone. Using P and S (SH) waves we find a steeply dipping reflector centred at ca. 400 km depth and ca. 550 km west of the present Mariana subduction zone (at 20N, 140E). The discovery of this anomaly in tomography and independently in array seismology (this paper) helps in understanding the evolution of the Mariana margin. The reflector/stagnant slab may be the remains of the hypothetical North New Guinea Plate, which was theorized to have subducted ca. 50 Ma.}, language = {en} } @article{KalbeMischkeDulskietal.2015, author = {Kalbe, Johannes and Mischke, Steffen and Dulski, Peter and Sharon, Gonen}, title = {The Middle Palaeolithic Nahal Mahanayeem Outlet site, Israel: reconstructing the environment of Late Pleistocene wetlands in the eastern Mediterranean from ostracods}, series = {Journal of archaeological science}, volume = {54}, journal = {Journal of archaeological science}, publisher = {Elsevier}, address = {London}, issn = {0305-4403}, doi = {10.1016/j.jas.2014.04.018}, pages = {385 -- 395}, year = {2015}, abstract = {We present ostracod data from the Middle Palaeolithic open air site of Nahal Mahanayeem Outlet (NMO) at the southern edge of the Hula Basin, northern Israel. Sediments of two Pleistocene water bodies are exposed at the site. The first one is an archaeologically sterile, light-colored limnic carbonate with an Early Pleistocene age. It contains an ostracod fauna assemblage dominated by Candona neglecta, Candonopsis kingsleii, and Pseudocandona sp., and, in minor abundances, Cypria ophtalmica, Cyprideis sp., Humphcypris sp., Fabaeformiscandona cf. fabaeformis and Ilyocypris sp. These sediments were deposited in a shallow, freshwater to oligohaline lake under stable conditions. Sediments of the second water body are silty and dark-colored with a depositional age of 65 ka, belonging to the Late Pleistocene Ashmura Formation. The unit covers a geologically complex topography of tectonically uplifted limnic deposits and a hill-like gravel bar at the site. The most important archaeological layer is situated at its base, containing a lithic assemblage ascribed primarily to the Middle Palaeolithic Mousterian tradition and very well preserved flora and fauna. In the sediments from the archaeological layers, the brackish water ostracod Cyprideis torosa and the foraminifer Ammonia tepida could be identified. In sediments of the Ashmura Formation taken near the site, C. neglecta, Candona angulata, Ilyogpris sp., C kingsleii, Pseudocandona sp., C ophtalmica, Darwinula stevensoni, Trajancypris sp. and Potamogpris smaragdina were found, indicating a freshwater to slightly oligohaline stagnant water body. The ostracod fauna of the NMO site, together with geochemical data, allow us to reconstruct a depositional environment of the margin at a shallow lake with brackish or saline springs nearby during the site's occupation by Middle Palaeolithic humans. Additionally, Candona weltneri, Candona cf. meerfeldiana, C kingsleii, Cyclocypris laevis, C ophtalmica, Cyprideis sp., Fabaeformiscandona cf. fabaeformis, P. smaragdina, Pseudocandona depressa, Trajancypris sp, Zonocypris cf. costata and A. tepida could be recorded for the first time for the Pleistocene limnic strata of the Hula Basin. (C) 2014 Elsevier Ltd. All rights reserved.}, language = {en} } @article{LeFriantIshizukaBoudonetal.2015, author = {Le Friant, A. and Ishizuka, O. and Boudon, G. and Palmer, M. R. and Talling, P. J. and Villemant, B. and Adachi, T. and Aljahdali, M. and Breitkreuz, C. and Brunet, M. and Caron, B. and Coussens, M. and Deplus, C. and Endo, D. and Feuillet, N. and Fraas, A. J. and Fujinawa, A. and Hart, M. B. and Hatfield, R. G. and Hornbach, M. and Jutzeler, M. and Kataoka, K. S. and Komorowski, J. -C. and Lebas, E. and Lafuerza, S. and Maeno, F. and Manga, M. and Martinez-Colon, M. and McCanta, M. and Morgan, S. and Saito, T. and Slagle, A. and Sparks, S. and Stinton, A. and Stroncik, Nicole and Subramanyam, K. S. V. and Tamura, Yui and Trofimovs, J. and Voight, B. and Wall-Palmer, D. and Wang, F. and Watt, S. F. L.}, title = {Submarine record of volcanic island construction and collapse in the Lesser Antilles arc: First scientific drilling of submarine volcanic island landslides by IODP Expedition 340}, series = {Geochemistry, geophysics, geosystems}, volume = {16}, journal = {Geochemistry, geophysics, geosystems}, number = {2}, publisher = {American Geophysical Union}, address = {Washington}, issn = {1525-2027}, doi = {10.1002/2014GC005652}, pages = {420 -- 442}, year = {2015}, abstract = {IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.}, language = {en} } @article{TronickeBoeniger2015, author = {Tronicke, Jens and Boeniger, Urs}, title = {Denoising magnetic data using steering kernel regression}, series = {Near surface geophysics}, volume = {13}, journal = {Near surface geophysics}, number = {1}, publisher = {European Association of Geoscientists \& Engineers}, address = {Houten}, issn = {1569-4445}, doi = {10.3997/1873-0604.2014038}, pages = {33 -- 44}, year = {2015}, abstract = {Ground-based magnetic surveying is a common geophysical method to explore near-surface environments in a non-destructive manner. In many typical applications (such as archaeological prospection), the resulting anomaly maps are often characterized by low signal-to-noise ratios and, thus, the suppression of noise is a key step in data processing. Here, we propose the steering kernel regression (SKR) method to denoise magnetic data sets. SKR has been recently developed to suppress random noise in images and video sequences. The core of the method is the steering kernel function which represents a robust estimate of local image structure. Using such a kernel within an iterative regression based denoising framework, helps to minimize image blurring and to preserve the underlying structures such as edges and corners. Because such filter characteristics are desirable for random noise attenuation in potential field data sets, we apply the SKR method for processing high-resolution ground-based magnetic data as they are typically collected in archaeological applications. We test and evaluate the SKR method using synthetic and field data examples and also compare it to more commonly employed denoising strategies relying, for example, on fixed filter masks (e.g., Gaussian filters). Our results show that the SKR method is successful in removing random and acquisition related noise present in our data. Concurrently, it preserves the local image structure including the amplitudes of anomalies. As demonstrated by derivative based transformations, the mentioned filter characteristics significantly impact subsequent processing steps and, therefore, result in an improved analysis and interpretation of magnetic data. Thus, the method can be considered as a promising and novel approach for denoising ground-based magnetic data.}, language = {en} } @article{HalamaKonradSchmolke2015, author = {Halama, Ralf and Konrad-Schmolke, Matthias}, title = {Retrograde metasomatic effects on phase assemblages in an interlayered blueschist-greenschist sequence (Coastal Cordillera, Chile)}, series = {Lithos : an international journal of mineralogy, petrology, and geochemistry}, volume = {216}, journal = {Lithos : an international journal of mineralogy, petrology, and geochemistry}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0024-4937}, doi = {10.1016/j.lithos.2014.12.004}, pages = {31 -- 47}, year = {2015}, abstract = {Interlayered blueschists and greenschists of the Coastal Cordillera (Chile) are part of a Late Palaeozoic accretionary complex. They represent metavolcanic rocks with oceanic affinities based on predominantly 01B-type REE patterns and immobile trace element ratios. Both rock types have similar mineralogies, albeit with different mineral modal abundances. Amphibole is the major mafic mineral and varies compositionally from glaucophane to actinolite. The presence of glaucophane relicts as cores in zoned amphiboles in both blueschists and greenschists is evidence for a pervasive high-pressure metamorphic stage, indicating that tectonic juxtaposition is an unlikely explanation for the cm-dm scale interlayering. During exhumation, a retrograde greenschist-facies overprint stabilized chlorite + albite + winchitic/actinolitic amphibole + phengitic white mica +/- epidote +/- K-feldspar at 0.4 +/- 0.1 GPa. Geochemical variability can be partly ascribed to primary magmatic and partly to secondary metasomatic processes that occurred under greenschist-facies conditions. Isocon diagrams of several adjacent blueschist-greenschist pairs with similar protolith geochemistry were used to evaluate metasomatic changes due to retrograde fluid-rock interaction. The most important geochemical changes are depletion of Si and Na and addition of water in the greenschists compared to the blueschists. Transition metals and LILE are mobilized to varying degrees. The unsystematic deviations from magmatic fractionation trends suggest open system conditions and influx of an external fluid. Pseudosection and water isopleth calculations show that the rocks were dehydrating during most of their exhumation history and remained at water-saturated conditions. The mineralogical changes, in particular breakdown of blue amphibole and replacement by chlorite, albite and calcic/sodic-calcic amphibole, are the prime cause for the distinct coloring. Pseudo-binary phase diagrams were used as a means to link bulk rock geochemical variability to modal and chemical changes in the mineralogy. The geochemical changes induced by fluid-rock interaction are important in two ways: First, the bulk rock chemistry is altered, leading to the stabilization of higher modal proportions of chlorite in the greenschists. Second, the retrograde overprint is a selective, layer-parallel fluid infiltration process, causing more intense greenschist-facies recrystallization in greenschist layers and therefore preferential preservation of blue amphibole in blueschist layers. Hence, the distinct colors were acquired by a combination of compositional variability, both primary magmatic and secondary metasomatic, and the different intensity of retrograde fluid infiltration. (C) 2014 Elsevier B.V. All rights reserved.}, language = {en} } @article{MielkeBoescheRogassetal.2015, author = {Mielke, Christian and B{\"o}sche, Nina Kristine and Rogass, Christian and Kaufmann, Hermann and Gauert, Christoph}, title = {New geometric hull continuum removal algorithm for automatic absorption band detection from spectroscopic data}, series = {Remote sensing letters : an official journal of the Remote Sensing and Photogrammetry Society}, volume = {6}, journal = {Remote sensing letters : an official journal of the Remote Sensing and Photogrammetry Society}, number = {2}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {2150-704X}, doi = {10.1080/2150704X.2015.1007246}, pages = {97 -- 105}, year = {2015}, abstract = {Modern imaging spectrometers produce an ever-growing amount of data, which increases the need for automated analysis techniques. The algorithms employed, such as the United States Geological Survey (USGS) Tetracorder and the Mineral Identification and Characterization Algorithm (MICA), use a standardized spectral library and expert knowledge for the detection of surface cover types. Correct absorption feature definition and isolation are key to successful material identification using these algorithms. Here, a new continuum removal and feature isolation technique is presented, named the 'Geometric Hull Technique'. It is compared to the well-established, knowledge-based Tetracorder feature database together with the adapted state of the art techniques scale-space filtering, alpha shapes and convex hull. The results show that the geometric hull technique yields the smallest deviations from the feature definitions of the MICA Group 2 library with a median difference of only 8nm for the position of the features and a median difference of only 15\% for the feature shapes. The modified scale-space filtering hull technique performs second best with a median feature position difference of 16nm and a median difference of 25\% for the feature shapes. The scale-space alpha hull technique shows a 23nm median position difference and a median deviation of 77\% for the feature shapes. The geometric hull technique proposed here performs best amongst the four feature isolation techniques and may be an important building block for next generation automatic mapping algorithms.}, language = {en} } @article{ParkStolleXiongetal.2015, author = {Park, Jaeheung and Stolle, Claudia and Xiong, Chao and L{\"u}hr, Hermann and Pfaff, Robert F. and Buchert, Stephan and Martinis, Carlos R.}, title = {A dayside plasma depletion observed at midlatitudes during quiet geomagnetic conditions}, series = {Geophysical research letters}, volume = {42}, journal = {Geophysical research letters}, number = {4}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1002/2014GL062655}, pages = {967 -- 974}, year = {2015}, abstract = {In this study we investigate a dayside, midlatitude plasma depletion (DMLPD) encountered on 22 May 2014 by the Swarm and GRACE satellites, as well as ground-based instruments. The DMLPD was observed near Puerto Rico by Swarm near 10 LT under quiet geomagnetic conditions at altitudes of 475-520 km and magnetic latitudes of similar to 25 degrees-30 degrees. The DMLPD was also revealed in total electron content observations by the Saint Croix station and by the GRACE satellites (430 km) near 16 LT and near the same geographic location. The unique Swarm constellation enables the horizontal tilt of the DMLPD to be measured (35 degrees clockwise from the geomagnetic east-west direction). Ground-based airglow images at Arecibo showed no evidence for plasma density depletions during the night prior to this dayside event. The C/NOFS equatorial satellite showed evidence for very modest plasma density depletions that had rotated into the morningside from nightside. However, the equatorial depletions do not appear related to the DMLPD, for which the magnetic apex height is about 2500 km. The origins of the DMLPD are unknown, but may be related to gravity waves.}, language = {en} } @article{FrijiaParenteDiLuciaetal.2015, author = {Frijia, Gianluca and Parente, Mariano and Di Lucia, Matteo and Mutti, Maria}, title = {Carbon and strontium isotope stratigraphy of the Upper Cretaceous (Cenomanian-Campanian) shallow-water carbonates of southern Italy: Chronostratigraphic calibration of larger foraminifera biostratigraphy}, series = {Cretaceous research}, volume = {53}, journal = {Cretaceous research}, publisher = {Elsevier}, address = {London}, issn = {0195-6671}, doi = {10.1016/j.cretres.2014.11.002}, pages = {110 -- 139}, year = {2015}, abstract = {Shallow-water carbonates are invaluable archives of past global change. They hold the record of how neritic biologic communities reacted to palaeoenvironmental changes. However, attempts to decipher these geological archives are often severely hampered by the low stratigraphic resolution attained by biostratigraphy. This is particularly the case for the Upper Cretaceous carbonate platforms of the central Tethyan realm: their biostratigraphy suffers from very low resolution and poor correlation with the standard biochronologic scales based on ammonites, planktic foraminifers and calcareous nannoplankton. In this paper we show how this problem can be tackled by integrating biostratigraphy with isotope stratigraphy. We present a detailed record of the benthic foraminiferal biostratigraphy and carbon and strontium isotope stratigraphy of three upper Cenomanian-middle Campanian sections belonging to the Apennine Carbonate Platform of southern Italy. For the upper Cenomanian-Turonian interval, the carbon isotope curves of the studied sections are easily correlated to the reference curve of the English Chalk. The correlation is facilitated by the matching of the prominent positive excursion corresponding to the Oceanic Anoxic Event 2. For the Coniacian-middle Campanian interval, the correlation is mainly based on strontium isotope stratigraphy. We use the Sr-87/Sr-86 ratios of the low-Mg calcite of well preserved rudist shells to obtain accurate chronostratigraphic ages for many levels of the three studied sections. The ages obtained by Sr isotope stratigraphy are then used to better constrain the matching of the carbon isotope curves. From the high-resolution chronostratigraphic age-model stablished by isotope stratigraphy, we derive the chronostratigraphic calibration of benthic foraminiferal biostratigraphic events. For the first time the benthic foraminiferal biozones of the Apennine Carbonate Platform can be accurately correlated to the standard ammonite biozonation. This result is of great relevance because the biostratigraphic schemes of other carbonate platforms in the central and southern Tethyan realm are largely based on the same biostratigraphic events. (C) 2014 Elsevier Ltd. All rights reserved.}, language = {en} } @unpublished{MischkeMadsenZhangetal.2015, author = {Mischke, Steffen and Madsen, David and Zhang, Chengjun and Lai, Zhongping}, title = {Reply to comment by Zhang (2014): The Shell Bar in the Qaidam Basin: fluvial or lake deposit, and OSL versus C-14 age data}, series = {Journal of paleolimnolog}, volume = {53}, journal = {Journal of paleolimnolog}, number = {3}, publisher = {Springer}, address = {Dordrecht}, issn = {0921-2728}, doi = {10.1007/s10933-014-9817-z}, pages = {335 -- 344}, year = {2015}, language = {en} }