TY - JOUR A1 - Zimmermann, Alexander A1 - Voss, Sebastian A1 - Metzger, Johanna Clara A1 - Hildebrandt, Anke A1 - Zimmermann, Beate T1 - estimating mean throughfall JF - Journal of hydrology N2 - The selection of an appropriate spatial extent of a sampling plot is one among several important decisions involved in planning a throughfall sampling scheme. In fact, the choice of the extent may determine whether or not a study can adequately characterize the hydrological fluxes of the studied ecosystem. Previous attempts to optimize throughfall sampling schemes focused on the selection of an appropriate sample size, support, and sampling design, while comparatively little attention has been given to the role of the extent. In this contribution, we investigated the influence of the extent on the representativeness of mean throughfall estimates for three forest ecosystems of varying stand structure. Our study is based on virtual sampling of simulated throughfall fields. We derived these fields from throughfall data sampled in a simply structured forest (young tropical forest) and two heterogeneous forests (old tropical forest, unmanaged mixed European beech forest). We then sampled the simulated throughfall fields with three common extents and various sample sizes for a range of events and for accumulated data. Our findings suggest that the size of the study area should be carefully adapted to the complexity of the system under study and to the required temporal resolution of the throughfall data (i.e. event-based versus accumulated). Generally, event-based sampling in complex structured forests (conditions that favor comparatively long autocorrelations in throughfall) requires the largest extents. For event-based sampling, the choice of an appropriate extent can be as important as using an adequate sample size. (C) 2016 Elsevier B.V. All rights reserved. KW - Throughfall KW - Sampling KW - Extent KW - Hydrological monitoring KW - Tropical forest KW - European beech forest Y1 - 2016 U6 - https://doi.org/10.1016/j.jhydrol.2016.09.047 SN - 0022-1694 SN - 1879-2707 VL - 542 SP - 781 EP - 789 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ziegler, Moritz O. A1 - Rajabi, Mojtaba A1 - Heidbach, Oliver A1 - Hersir, Gylfi Pall A1 - Agustsson, Kristjan A1 - Arnadottir, Sigurveig A1 - Zang, Arno T1 - The stress pattern of Iceland JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - Iceland is located on the Mid-Atlantic Ridge which is the plate boundary between the Eurasian and the North American plates. It is one of the few places on earth where an active spreading centre is located onshore but the stress pattern has not been extensively investigated so far. In this paper we present a comprehensive compilation of the orientation of maximum horizontal stress (S-Hmax). In particular we interpret borehole breakouts and drilling induced fractures from borehole image logs in 57 geothermal wells onshore Iceland. The borehole results are combined with other stress indicators including earthquake focal mechanism solutions, geological information and overcoring measurements resulting in a dataset with 495 data records for the S-Hmax orientation. The reliability of each indicator is assessed according to the quality criteria of the World Stress Map project The majority of S-Hmax orientation data records in Iceland is derived from earthquake focal mechanism solutions (35%) and geological fault slip inversions (26%). 20% of the data are borehole related stress indicators. In addition minor shares of S-Hmax orientations are compiled, amongst others, from focal mechanism inversions and the alignment of fissure eruptions. The results show that the S-Hmax orientations derived from different depths and stress indicators are consistent with each other. The resulting pattern of the present-day stress in Iceland has four distinct subsets of S-Hmax orientations. The S-Hmax orientation is parallel to the rift axes in the vicinity of the active spreading regions. It changes from NE-SW in the South to approximately N-S in central Iceland and NNW-SSE in the North. In the Westfjords which is located far away from the ridge the regional S-Hmax rotates and is parallel to the plate motion. (C) 2016 Elsevier B.V. All rights reserved. KW - Iceland KW - Stress field KW - Stress pattern KW - Borehole image logs Y1 - 2016 U6 - https://doi.org/10.1016/j.tecto.2016.02.008 SN - 0040-1951 SN - 1879-3266 VL - 674 SP - 101 EP - 113 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ziegler, Moritz O. A1 - Heidbach, Oliver A1 - Reinecker, John A1 - Przybycin, Anna M. A1 - Scheck-Wenderoth, Magdalena T1 - A multi-stage 3-D stress field modelling approach exemplified in the Bavarian Molasse Basin JF - Solid earth Y1 - 2016 U6 - https://doi.org/10.5194/se-7-1365-2016 SN - 1869-9510 SN - 1869-9529 VL - 7 SP - 1365 EP - 1382 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Zibulski, Romy A1 - Herzschuh, Ulrike A1 - Pestryakova, Luidmila Agafyevna T1 - Vegetation patterns along micro-relief and vegetation type transects in polygonal landscapes of the Siberian Arctic JF - Journal of vegetation science N2 - QuestionHow important is the effect of micro-relief and vegetation type on the characteristics of vascular plants and bryophytes in low-centred polygons? LocationSiberian Arctic, Russia. MethodsEight low-centred polygons in northern Siberia were surveyed for vegetation along transects running from the rim to the pond via the rim-pond transition of each polygon and across a vegetation type gradient from open forest to tundra. ResultsThe cover of vascular plants and bryophytes displays no significant differences between the rim and rim-pond transition but is significantly lower in the pond section of the polygons. Alpha-diversity of vascular plants decreases strongly from rim to pond, whereas bryophyte diversity in pond plots is significantly distinct from the rim and the rim-pond transition. There is no clear trend in cover for either plant group along the vegetation type transect and only a weak trend in -diversity. However, both gradients are reflected in the compositional turnover. The applied indicator species analysis identified taxa characteristic of certain environmental conditions. Among others, we found vascular plants primarily characteristic of the rim and bryophyte taxa characteristic of each micro-relief level and vegetation type. ConclusionsThe observed gradual pattern in -diversity and composition of polygonal vegetation suggests that micro-relief is the main driver of changes in the vegetation composition, while vegetation type and the related forest cover change are of subordinate importance for polygonal vegetation patterns along the Siberian tree line. KW - Bryophytes KW - Indicator species KW - Low-centred polygon KW - NMDS KW - Russia KW - Tree line KW - Tundra KW - Vascular plants Y1 - 2016 U6 - https://doi.org/10.1111/jvs.12356 SN - 1100-9233 SN - 1654-1103 VL - 27 SP - 377 EP - 386 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Zhou, Renjie A1 - Schoenbohm, Lindsay M. A1 - Sobel, Edward A1 - Carrapa, Barbara A1 - Davis, Donald W. T1 - Sedimentary record of regional deformation and dynamics of the thick-skinned southern Puna Plateau, central Andes (26-27 degrees S) JF - Earth & planetary science letters N2 - The Puna Plateau, adjacent Eastern Cordillera and the Sierras Pampeanas of the central Andes are largely characterized by thick-skinned, basement-involved deformation. The Puna Plateau hosts similar to N-S trending bedrock ranges bounded by deep-seated reverse faults and sedimentary basins. We contribute to the understanding of thick-skinned dynamics in the Puna Plateau by constraining regional kinematics of the poorly understood southern Puna Plateau through a multidisciplinary approach. On the southeastern plateau, sandstone modal composition and detrital zircon U-Pb and apatite fission-track data from Cenozoic strata indicate basin accumulation during the late Eocene to early Oligocene (similar to 38-28 Ma). Provenance analysis reveals the existence of a regional-scale basin covering the southern Puna Plateau during late Eocene to early Oligocene time (similar to 38-28 Ma) that was sourced from both the western plateau and the eastern plateau margin and had a depocenter located to the west. Petrographic and detrital zircon U-Pb data reveal erosion of proximal western and eastern sources after 12 Ma, in mid-late Miocene time. This indicates that the regional basin was compartmentalized into small-scale depocenters by the growth of basement-cored ranges continuing into the late Miocene (similar to 12-8 Ma). We suggest that the Cenozoic history of the southern Puna Plateau records the formation of a regional basin that was possibly driven by lithospheric flexure during the late Eocene to early Oligocene, before the growth of distributed basement-cored ranges starting as early as the late Oligocene. (C) 2015 Elsevier B.V. All rights reserved. KW - Puna Plateau KW - regional deformation KW - basin analysis KW - thick-skinned deformation KW - zircon U-Pb geochronology KW - apatite fission-track thermochronology Y1 - 2016 U6 - https://doi.org/10.1016/j.epsl.2015.11.012 SN - 0012-821X SN - 1385-013X VL - 433 SP - 317 EP - 325 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Zhou, Bin A1 - Lauwaet, Dirk A1 - Hooyberghs, Hans A1 - De Ridder, Koen A1 - Kropp, Jürgen A1 - Rybski, Diego T1 - Assessing Seasonality in the Surface Urban Heat Island of London JF - Journal of applied meteorology and climatology N2 - This paper assesses the seasonality of the urban heat island (UHI) effect in the Greater London area (United Kingdom). Combining satellite-based observations and urban boundary layer climate modeling with the UrbClim model, the authors are able to address the seasonality of UHI intensity, on the basis of both land surface temperature (LST) and 2-m air temperature, for four individual times of the day (0130, 1030, 1330, and 2230 local time) and the daily means derived from them. An objective of this paper is to investigate whether the UHI intensities that are based on both quantities exhibit a similar hysteresis-like trajectory that is observed for LST when plotting the UHI intensity against the background temperature. The results show that the UrbClim model can satisfactorily reproduce both the observed urban rural LSTs and 2-m air temperatures as well as their differences and the hysteresis in the surface UHI. The hysteresis-like seasonality is largely absent in both the observed and modeled 2-m air temperatures, however. A sensitivity simulation of the UHI intensity to incoming solar radiation suggests that the hysteresis of the LST can mainly be attributed to the seasonal variation in incoming solar radiation. Y1 - 2016 U6 - https://doi.org/10.1175/JAMC-D-15-0041.1 SN - 1558-8424 SN - 1558-8432 VL - 55 SP - 493 EP - 505 PB - American Meteorological Soc. CY - Boston ER - TY - JOUR A1 - Zhang, Shengrui A1 - Xu, Qinghai A1 - Gaillard, Marie-Jose A1 - Cao, Xianyong A1 - Li, Jianyong A1 - Zhang, Liyan A1 - Li, Yuecong A1 - Tian, Fang A1 - Zhou, Liping A1 - Lin, Fengyou A1 - Yang, Xiaolan T1 - Characteristic pollen source area and vertical pollen dispersal and deposition in a mixed coniferous and deciduous broad-leaved woodland in the Changbai mountains, northeast China JF - Vegetation History and Archaeobotany N2 - Pollen influx (number of pollen grains cm−2 year−1) can objectively reflect the dispersal and deposition features of pollen within a certain time and space, and is often used as a basis for the quantitative reconstruction of palaeovegetation; however, little is known about the features and mechanisms of vertical dispersal of pollen. Here we present the results from a 5 year (2006–2010) monitoring program using pollen traps placed at different heights from ground level up to 60 m and surface soil samples in a mixed coniferous and deciduous broad-leaved woodland in the Changbai mountains, northeastern China. The pollen percentages and pollen influx from the traps have very similar characteristics to the highest values for Betula, Fraxinus, Quercus and Pinus, among the tree taxa and Artemisia, Chenopodiaceae and Asteraceae among the herb taxa. Pollen influx values vary significantly with height and show major differences between three distinct layers, above-canopy (≥32 m), within the trunk layer (8 ≤ 32 m) and on the ground (0 m). These differences in pollen influx are explained by differences in (i) the air flows in each of these layers and (ii) the fall speed of pollen of the various taxa. We found that the pollen recorded on the ground surface is a good representation of the major part of the pollen transported in the trunk space of the woodland. Comparison of the pollen influx values with the theoretical, calculated “characteristic pollen source area” (CPSA) of 12 selected taxa indicates that the pollen deposited on the ground surface of the woodland is a fair representation with 85–90 % of the total pollen deposited at a wind speed of 2.4 m s−1 coming from within ca. 1–5 km for Pinus and Quercus, ca. 5–10 km for Ulmus, Tilia, Oleaceae and Betula, ca. 20–40 km for Fraxinus, Poaceae, Chenopodiaceae, Populus and Salix, and ca. 30–60 km for Artemisia; it is also a good representation with 90–98 % of the total pollen deposited coming from within 60 km at a wind speed of 2.4 m s−1, or 100 km at a wind speed: 6 m s−1, for the 12 selected taxa used in the CPSA calculation. Furthermore, comparison with the vegetation map of the area around the sampling site shows that the pollen deposited on the ground represents all plant communities which grow in the study area within 70 km radius of the sampling site. In this study, the pollen percentages obtained from the soil surface samples are significantly biased towards pollen taxa with good preservation due to thick and robust pollen walls. Therefore, if mosses are available instead, soil samples should be avoided for pollen studies, in particular for the study of pollen-vegetation relationships, the estimation of pollen productivities and quantitative reconstruction of past vegetation. The results also indicate that the existing model of pollen dispersal and deposition, Prentice’s model, provides a fair description of the actual pollen dispersal and deposition in this kind of woodland, which suggests that the application of the landscape reconstruction algorithm would be relevant for reconstruction of this type of woodland in the past. KW - Changbai mountains KW - Mixed coniferous and deciduous broad-leaved woodland KW - Vertical pollen dispersal and deposition KW - Characteristic pollen source area Y1 - 2016 U6 - https://doi.org/10.1007/s00334-015-0532-0 SN - 0939-6314 SN - 1617-6278 VL - 25 SP - 29 EP - 43 PB - Springer CY - New York ER - TY - JOUR A1 - Yepes, Hugo A1 - Audin, Laurence A1 - Alvarado, Alexandra A1 - Beauval, Celine A1 - Aguilar, Jorge A1 - Font, Yvonne A1 - Cotton, Fabrice Pierre T1 - A new view for the geodynamics of Ecuador: Implication in seismogenic source definition and seismic hazard assessment JF - Tectonics N2 - A new view of Ecuador's complex geodynamics has been developed in the course of modeling seismic source zones for probabilistic seismic hazard analysis. This study focuses on two aspects of the plates' interaction at a continental scale: (a) age-related differences in rheology between Farallon and Nazca plates—marked by the Grijalva rifted margin and its inland projection—as they subduct underneath central Ecuador, and (b) the rapidly changing convergence obliquity resulting from the convex shape of the South American northwestern continental margin. Both conditions satisfactorily explain several characteristics of the observed seismicity and of the interseismic coupling. Intermediate-depth seismicity reveals a severe flexure in the Farallon slab as it dips and contorts at depth, originating the El Puyo seismic cluster. The two slabs position and geometry below continental Ecuador also correlate with surface expressions observable in the local and regional geology and tectonics. The interseismic coupling is weak and shallow south of the Grijalva rifted margin and increases northward, with a heterogeneous pattern locally associated to the Carnegie ridge subduction. High convergence obliquity is responsible for the North Andean Block northeastward movement along localized fault systems. The Cosanga and Pallatanga fault segments of the North Andean Block-South American boundary concentrate most of the seismic moment release in continental Ecuador. Other inner block faults located along the western border of the inter-Andean Depression also show a high rate of moderate-size earthquake production. Finally, a total of 19 seismic source zones were modeled in accordance with the proposed geodynamic and neotectonic scheme. Y1 - 2016 U6 - https://doi.org/10.1002/2015TC003941 SN - 0278-7407 SN - 1944-9194 VL - 35 SP - 1249 EP - 1279 PB - American Geophysical Union CY - Washington ER - TY - GEN A1 - Xiong, Chao A1 - Stolle, Claudia A1 - Lühr, Hermann A1 - Park, Jaeheung A1 - Fejer, Bela G. A1 - Kervalishvili, Guram N. T1 - Scale analysis of equatorial plasma irregularities derived from Swarm constellation T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - In this study, we investigated the scale sizes of equatorial plasma irregularities (EPIs) using measurements from the Swarm satellites during its early mission and final constellation phases. We found that with longitudinal separation between Swarm satellites larger than 0.4°, no significant correlation was found any more. This result suggests that EPI structures include plasma density scale sizes less than 44 km in the zonal direction. During the Swarm earlier mission phase, clearly better EPI correlations are obtained in the northern hemisphere, implying more fragmented irregularities in the southern hemisphere where the ambient magnetic field is low. The previously reported inverted-C shell structure of EPIs is generally confirmed by the Swarm observations in the northern hemisphere, but with various tilt angles. From the Swarm spacecrafts with zonal separations of about 150 km, we conclude that larger zonal scale sizes of irregularities exist during the early evening hours (around 1900 LT). T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1112 KW - Equatorial plasma irregularities KW - ionospheric scale lengths KW - Swarm constellation Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-431842 SN - 1866-8372 IS - 1112 ER - TY - JOUR A1 - Xiong, Chao A1 - Stolle, Claudia A1 - Luehr, Hermann A1 - Park, Jaeheung A1 - Fejer, Bela G. A1 - Kervalishvili, Guram N. T1 - Scale analysis of equatorial plasma irregularities derived from Swarm constellation JF - Earth, planets and space N2 - In this study, we investigated the scale sizes of equatorial plasma irregularities (EPIs) using measurements from the Swarm satellites during its early mission and final constellation phases. We found that with longitudinal separation between Swarm satellites larger than 0.4 degrees, no significant correlation was found any more. This result suggests that EPI structures include plasma density scale sizes less than 44 km in the zonal direction. During the Swarm earlier mission phase, clearly better EPI correlations are obtained in the northern hemisphere, implying more fragmented irregularities in the southern hemisphere where the ambient magnetic field is low. The previously reported inverted-C shell structure of EPIs is generally confirmed by the Swarm observations in the northern hemisphere, but with various tilt angles. From the Swarm spacecrafts with zonal separations of about 150 km, we conclude that larger zonal scale sizes of irregularities exist during the early evening hours (around 1900 LT). KW - Equatorial plasma irregularities KW - Ionospheric scale lengths KW - Swarm constellation Y1 - 2016 U6 - https://doi.org/10.1186/s40623-016-0502-5 SN - 1880-5981 VL - 68 SP - 189 EP - 202 PB - Springer CY - Heidelberg ER -