TY - JOUR
A1 - Agarwal, Ankit
A1 - Marwan, Norbert
A1 - Maheswaran, Rathinasamy
A1 - Öztürk, Ugur
A1 - Kurths, Jürgen
A1 - Merz, Bruno
T1 - Optimal design of hydrometric station networks based on complex network analysis
JF - Hydrology and Earth System Sciences
N2 - Hydrometric networks play a vital role in providing information for decision-making in water resource management. They should be set up optimally to provide as much information as possible that is as accurate as possible and, at the same time, be cost-effective. Although the design of hydrometric networks is a well-identified problem in hydrometeorology and has received considerable attention, there is still scope for further advancement. In this study, we use complex network analysis, defined as a collection of nodes interconnected by links, to propose a new measure that identifies critical nodes of station networks. The approach can support the design and redesign of hydrometric station networks. The science of complex networks is a relatively young field and has gained significant momentum over the last few years in different areas such as brain networks, social networks, technological networks, or climate networks. The identification of influential nodes in complex networks is an important field of research. We propose a new node-ranking measure – the weighted degree–betweenness (WDB) measure – to evaluate the importance of nodes in a network. It is compared to previously proposed measures used on synthetic sample networks and then applied to a real-world rain gauge network comprising 1229 stations across Germany to demonstrate its applicability. The proposed measure is evaluated using the decline rate of the network efficiency and the kriging error. The results suggest that WDB effectively quantifies the importance of rain gauges, although the benefits of the method need to be investigated in more detail.
KW - identifying influential nodes
KW - climate networks
KW - rainfall
KW - streamflow
KW - synchronization
KW - precipitation
KW - classification
KW - events
Y1 - 2020
U6 - https://doi.org/10.5194/hess-24-2235-2020
SN - 1027-5606
SN - 1607-7938
VL - 24
IS - 5
SP - 2235
EP - 2251
PB - Copernicus Publ.
CY - Göttingen
ER -
TY - GEN
A1 - Agarwal, Ankit
A1 - Marwan, Norbert
A1 - Maheswaran, Rathinasamy
A1 - Öztürk, Ugur
A1 - Kurths, Jürgen
A1 - Merz, Bruno
T1 - Optimal design of hydrometric station networks based on complex network analysis
T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - Hydrometric networks play a vital role in providing information for decision-making in water resource management. They should be set up optimally to provide as much information as possible that is as accurate as possible and, at the same time, be cost-effective. Although the design of hydrometric networks is a well-identified problem in hydrometeorology and has received considerable attention, there is still scope for further advancement. In this study, we use complex network analysis, defined as a collection of nodes interconnected by links, to propose a new measure that identifies critical nodes of station networks. The approach can support the design and redesign of hydrometric station networks. The science of complex networks is a relatively young field and has gained significant momentum over the last few years in different areas such as brain networks, social networks, technological networks, or climate networks. The identification of influential nodes in complex networks is an important field of research. We propose a new node-ranking measure – the weighted degree–betweenness (WDB) measure – to evaluate the importance of nodes in a network. It is compared to previously proposed measures used on synthetic sample networks and then applied to a real-world rain gauge network comprising 1229 stations across Germany to demonstrate its applicability. The proposed measure is evaluated using the decline rate of the network efficiency and the kriging error. The results suggest that WDB effectively quantifies the importance of rain gauges, although the benefits of the method need to be investigated in more detail.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 951
KW - identifying influential nodes
KW - climate networks
KW - rainfall
KW - streamflow
KW - synchronization
KW - precipitation
KW - classification
KW - events
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-471006
SN - 1866-8372
IS - 951
ER -
TY - JOUR
A1 - Albrecht, Torsten
A1 - Winkelmann, Ricarda
A1 - Levermann, Anders
T1 - Glacial-cycle simulations of the Antarctic Ice Sheet with the Parallel Ice Sheet Model (PISM)
BT - Part 1: boundary conditions and climatic forcing
JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
N2 - Simulations of the glacial-interglacial history of the Antarctic Ice Sheet provide insights into dynamic threshold behavior and estimates of the ice sheet's contributions to global sea-level changes for the past, present and future. However, boundary conditions are weakly constrained, in particular at the interface of the ice sheet and the bedrock. Also climatic forcing covering the last glacial cycles is uncertain, as it is based on sparse proxy data.
We use the Parallel Ice Sheet Model (PISM) to investigate the dynamic effects of different choices of input data, e.g., for modern basal heat flux or reconstructions of past changes of sea level and surface temperature. As computational resources are limited, glacial-cycle simulations are performed using a comparably coarse model grid of 16 km and various parameterizations, e.g., for basal sliding, iceberg calving, or for past variations in precipitation and ocean temperatures. In this study we evaluate the model's transient sensitivity to corresponding parameter choices and to different boundary conditions over the last two glacial cycles and provide estimates of involved uncertainties. We also discuss isolated and combined effects of climate and sea-level forcing. Hence, this study serves as a "cookbook" for the growing community of PISM users and paleo-ice sheet modelers in general.
For each of the different model uncertainties with regard to climatic forcing, ice and Earth dynamics, and basal processes, we select one representative model parameter that captures relevant uncertainties and motivates corresponding parameter ranges that bound the observed ice volume at present. The four selected parameters are systematically varied in a parameter ensemble analysis, which is described in a companion paper.
Y1 - 2020
U6 - https://doi.org/10.5194/tc-14-599-2020
SN - 1994-0416
SN - 1994-0424
VL - 14
IS - 2
SP - 599
EP - 632
PB - Copernicus
CY - Göttingen
ER -
TY - JOUR
A1 - Allroggen, Niklas
A1 - Beiter, Daniel
A1 - Tronicke, Jens
T1 - Ground-penetrating radar monitoring of fast subsurface processes
JF - Geophysics
N2 - Earth and environmental sciences rely on detailed information about subsurface processes. Whereas geophysical techniques typically provide highly resolved spatial images, monitoring subsurface processes is often associated with enormous effort and, therefore, is usually limited to point information in time or space. Thus, the development of spatial and temporal continuous field monitoring methods is a major challenge for the understanding of subsurface processes. We have developed a novel method for ground-penetrating-radar (GPR) reflection monitoring of subsurface flow processes under unsaturated conditions and applied it to a hydrological infiltration experiment performed across a periglacial slope deposit in northwest Luxembourg. Our approach relies on a spatial and temporal quasicontinuous data recording and processing, followed by an attribute analysis based on analyzing differences between individual time steps. The results demonstrate the ability of time-lapse GPR monitoring to visualize the spatial and temporal dynamics of preferential flow processes with a spatial resolution in the order of a few decimeters and temporal resolution in the order of a few minutes. We observe excellent agreement with water table information originating from different boreholes. This demonstrates the potential of surface-based GPR reflection monitoring to observe the spatiotemporal dynamics of water movements in the subsurface. It provides valuable, and so far not accessible, information for example in the field of hydrology and pedology that allows studying the actual subsurface processes rather than deducing them from point information.
Y1 - 2020
U6 - https://doi.org/10.1190/GEO2019-0737.1
SN - 0016-8033
SN - 1942-2156
VL - 85
IS - 3
SP - A19
EP - A23
PB - Society of Exploration Geophysicists
CY - Tulsa
ER -
TY - THES
A1 - Angelopoulos, Michael
T1 - Mechanisms of sub-aquatic permafrost evolution in Arctic coastal environments
BT - field observations and modelling of submerged ice-rich permafrost deposits and thermokarst lagoons in northeastern Siberia
N2 - Subsea permafrost is perennially cryotic earth material that lies offshore. Most submarine permafrost is relict terrestrial permafrost beneath the Arctic shelf seas, was inundated after the last glaciation, and has been warming and thawing ever since. It is a reservoir and confining layer for gas hydrates and has the potential to release greenhouse gases and affect global climate change. Furthermore, subsea permafrost thaw destabilizes coastal infrastructure. While numerous studies focus on its distribution and rate of thaw over glacial timescales, these studies have not been brought together and examined in their entirety to assess rates of thaw beneath the Arctic Ocean. In addition, there is still a large gap in our understanding of sub-aquatic permafrost processes on finer spatial and temporal scales. The degradation rate of subsea permafrost is influenced by the initial conditions upon submergence. Terrestrial permafrost that has already undergone warming, partial thawing or loss of ground ice may react differently to inundation by seawater compared to previously undisturbed ice-rich permafrost. Heat conduction models are sufficient to model the thaw of thick subsea permafrost from the bottom, but few studies have included salt diffusion for top-down chemical degradation in shallow waters characterized by mean annual cryotic conditions on the seabed. Simulating salt transport is critical for assessing degradation rates for recently inundated permafrost, which may accelerate in response to warming shelf waters, a lengthening open water season, and faster coastal erosion rates. In the nearshore zone, degradation rates are also controlled by seasonal processes like bedfast ice, brine injection, seasonal freezing under floating ice conditions and warm freshwater discharge from large rivers. The interplay of all these variables is complex and needs further research. To fill this knowledge gap, this thesis investigates sub-aquatic permafrost along the southern coast of the Bykovsky Peninsula in eastern Siberia. Sediment cores and ground temperature profiles were collected at a freshwater thermokarst lake and two thermokarst lagoons in 2017. At this site, the coastline is retreating, and seawater is inundating various types of permafrost: sections of ice-rich Pleistocene permafrost (Yedoma) cliffs at the coastline alternate with lagoons and lower elevation previously thawed and refrozen permafrost basins (Alases). Electrical resistivity surveys with floating electrodes were carried out to map ice-bearing permafrost and taliks (unfrozen zones in the permafrost, usually formed beneath lakes) along the diverse coastline and in the lagoons. Combined with the borehole data, the electrical resistivity results permit estimation of contemporary ice-bearing permafrost characteristics, distribution, and occasionally, thickness. To conceptualize possible geomorphological and marine evolutionary pathways to the formation of the observed layering, numerical models were applied. The developed model incorporates salt diffusion and seasonal dynamics at the seabed, including bedfast ice. Even along coastlines with mean annual non-cryotic boundary conditions like the Bykovsky Peninsula, the modelling results show that salt diffusion minimizes seasonal freezing of the seabed, leading to faster degradation rates compared to models without salt diffusion. Seasonal processes are also important for thermokarst lake to lagoon transitions because lagoons can generate cold hypersaline conditions underneath the ice cover. My research suggests that ice-bearing permafrost can form in a coastal lagoon environment, even under floating ice. Alas basins, however, may degrade more than twice as fast as Yedoma permafrost in the first several decades of inundation. In addition to a lower ice content compared to Yedoma permafrost, Alas basins may be pre-conditioned with salt from adjacent lagoons. Considering the widespread distribution of thermokarst in the Arctic, its integration into geophysical models and offshore surveys is important to quantify and understand subsea permafrost degradation and aggradation. Through numerical modelling, fieldwork, and a circum-Arctic review of subsea permafrost literature, this thesis provides new insights into sub-aquatic permafrost evolution in saline coastal environments.
KW - permafrost
KW - subsea
KW - submarine
KW - thermokarst
KW - lagoons
KW - salt diffusion
KW - electrical resistivity
Y1 - 2020
ER -
TY - JOUR
A1 - Angelopoulos, Michael
A1 - Overduin, Pier Paul
A1 - Westermann, Sebastian
A1 - Tronicke, Jens
A1 - Strauss, Jens
A1 - Schirrmeister, Lutz
A1 - Biskaborn, Boris
A1 - Liebner, Susanne
A1 - Maksimov, Georgii
A1 - Grigoriev, Mikhail N.
A1 - Grosse, Guido
T1 - Thermokarst lake to lagoon transitions in Eastern Siberia
BT - do submerged taliks refreeze?
JF - Journal of geophysical research : Earth surface
N2 - As the Arctic coast erodes, it drains thermokarst lakes, transforming them into lagoons, and, eventually, integrates them into subsea permafrost. Lagoons represent the first stage of a thermokarst lake transition to a marine setting and possibly more saline and colder upper boundary conditions. In this research, borehole data, electrical resistivity surveying, and modeling of heat and salt diffusion were carried out at Polar Fox Lagoon on the Bykovsky Peninsula, Siberia. Polar Fox Lagoon is a seasonally isolated water body connected to Tiksi Bay through a channel, leading to hypersaline waters under the ice cover. The boreholes in the center of the lagoon revealed floating ice and a saline cryotic bed underlain by a saline cryotic talik, a thin ice-bearing permafrost layer, and unfrozen ground. The bathymetry showed that most of the lagoon had bedfast ice in spring. In bedfast ice areas, the electrical resistivity profiles suggested that an unfrozen saline layer was underlain by a thick layer of refrozen talik. The modeling showed that thermokarst lake taliks can refreeze when submerged in saltwater with mean annual bottom water temperatures below or slightly above 0 degrees C. This occurs, because the top-down chemical degradation of newly formed ice-bearing permafrost is slower than the refreezing of the talik. Hence, lagoons may precondition taliks with a layer of ice-bearing permafrost before encroachment by the sea, and this frozen layer may act as a cap on gas migration out of the underlying talik.
KW - thermokarst lake
KW - talik
KW - lagoon
KW - subsea permafrost
KW - salt diffusion
KW - Siberia
Y1 - 2020
U6 - https://doi.org/10.1029/2019JF005424
SN - 2169-9003
SN - 2169-9011
VL - 125
IS - 10
PB - American Geophysical Union
CY - Washington
ER -
TY - JOUR
A1 - Arnous, Ahmad
A1 - Zeckra, Martin
A1 - Venerdini, Agostina
A1 - Alvarado, Patricia
A1 - Arrowsmith, Ramón
A1 - Guillemoteau, Julien
A1 - Landgraf, Angela
A1 - Gutiérrez, Adolfo Antonio
A1 - Strecker, Manfred
T1 - Neotectonic Activity in the Low-Strain Broken Foreland (Santa Bárbara System) of the North-Western Argentinean Andes (26°S)
JF - Lithosphere
N2 - Uplift in the broken Andean foreland of the Argentine Santa Bárbara System (SBS) is associated with the contractional reactivation of basement anisotropies, similar to those reported from the thick-skinned Cretaceous-Eocene Laramide province of North America. Fault scarps, deformed Quaternary deposits and landforms, disrupted drainage patterns, and medium-sized earthquakes within the SBS suggest that movement along these structures may be a recurring phenomenon, with yet to be defined repeat intervals and rupture lengths. In contrast to the Subandes thrust belt farther north, where eastward-migrating deformation has generated a well-defined thrust front, the SBS records spatiotemporally disparate deformation along structures that are only known to the first order. We present herein the results of geomorphic desktop analyses, structural field observations, and 2D electrical resistivity tomography and seismic-refraction tomography surveys and an interpretation of seismic reflection profiles across suspected fault scarps in the sedimentary basins adjacent to the Candelaria Range (CR) basement uplift, in the south-central part of the SBS. Our analysis in the CR piedmont areas reveals consistency between the results of near-surface electrical resistivity and seismic-refraction tomography surveys, the locations of prominent fault scarps, and structural geometries at greater depth imaged by seismic reflection data. We suggest that this deformation is driven by deep-seated blind thrusting beneath the CR and associated regional warping, while shortening involving Mesozoic and Cenozoic sedimentary strata in the adjacent basins was accommodated by layer-parallel folding and flexural-slip faults that cut through Quaternary landforms and deposits at the surface.
Y1 - 2019
U6 - https://doi.org/10.2113/2020/8888588
SN - 1947-4253
SN - 1941-8264
VL - 2020
IS - 1
SP - 1
EP - 25
PB - GSA
CY - Boulder, Colo.
ER -
TY - GEN
A1 - Arnous, Ahmad
A1 - Zeckra, Martin
A1 - Venerdini, Agostina
A1 - Alvarado, Patricia
A1 - Arrowsmith, Ramón
A1 - Guillemoteau, Julien
A1 - Landgraf, Angela
A1 - Gutiérrez, Adolfo Antonio
A1 - Strecker, Manfred
T1 - Neotectonic Activity in the Low-Strain Broken Foreland (Santa Bárbara System) of the North-Western Argentinean Andes (26°S)
T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2 - Uplift in the broken Andean foreland of the Argentine Santa Bárbara System (SBS) is associated with the contractional reactivation of basement anisotropies, similar to those reported from the thick-skinned Cretaceous-Eocene Laramide province of North America. Fault scarps, deformed Quaternary deposits and landforms, disrupted drainage patterns, and medium-sized earthquakes within the SBS suggest that movement along these structures may be a recurring phenomenon, with yet to be defined repeat intervals and rupture lengths. In contrast to the Subandes thrust belt farther north, where eastward-migrating deformation has generated a well-defined thrust front, the SBS records spatiotemporally disparate deformation along structures that are only known to the first order. We present herein the results of geomorphic desktop analyses, structural field observations, and 2D electrical resistivity tomography and seismic-refraction tomography surveys and an interpretation of seismic reflection profiles across suspected fault scarps in the sedimentary basins adjacent to the Candelaria Range (CR) basement uplift, in the south-central part of the SBS. Our analysis in the CR piedmont areas reveals consistency between the results of near-surface electrical resistivity and seismic-refraction tomography surveys, the locations of prominent fault scarps, and structural geometries at greater depth imaged by seismic reflection data. We suggest that this deformation is driven by deep-seated blind thrusting beneath the CR and associated regional warping, while shortening involving Mesozoic and Cenozoic sedimentary strata in the adjacent basins was accommodated by layer-parallel folding and flexural-slip faults that cut through Quaternary landforms and deposits at the surface.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1008
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-480183
SN - 1866-8372
IS - 1008
SP - 1
EP - 25
ER -
TY - GEN
A1 - Ayzel, Georgy
A1 - Scheffer, Tobias
A1 - Heistermann, Maik
T1 - RainNet v1.0
BT - a convolutional neural network for radar-based precipitation nowcasting
T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - In this study, we present RainNet, a deep convolutional neural network for radar-based precipitation nowcasting. Its design was inspired by the U-Net and SegNet families of deep learning models, which were originally designed for binary segmentation tasks. RainNet was trained to predict continuous precipitation intensities at a lead time of 5min, using several years of quality-controlled weather radar composites provided by the German Weather Service (DWD). That data set covers Germany with a spatial domain of 900km × 900km and has a resolution of 1km in space and 5min in time. Independent verification experiments were carried out on 11 summer precipitation events from 2016 to 2017. In order to achieve a lead time of 1h, a recursive approach was implemented by using RainNet predictions at 5min lead times as model inputs for longer lead times. In the verification experiments, trivial Eulerian persistence and a conventional model based on optical flow served as benchmarks. The latter is available in the rainymotion library and had previously been shown to outperform DWD's operational nowcasting model for the same set of verification events.
RainNet significantly outperforms the benchmark models at all lead times up to 60min for the routine verification metrics mean absolute error (MAE) and the critical success index (CSI) at intensity thresholds of 0.125, 1, and 5mm h⁻¹. However, rainymotion turned out to be superior in predicting the exceedance of higher intensity thresholds (here 10 and 15mm h⁻¹). The limited ability of RainNet to predict heavy rainfall intensities is an undesirable property which we attribute to a high level of spatial smoothing introduced by the model. At a lead time of 5min, an analysis of power spectral density confirmed a significant loss of spectral power at length scales of 16km and below. Obviously, RainNet had learned an optimal level of smoothing to produce a nowcast at 5min lead time. In that sense, the loss of spectral power at small scales is informative, too, as it reflects the limits of predictability as a function of spatial scale. Beyond the lead time of 5min, however, the increasing level of smoothing is a mere artifact – an analogue to numerical diffusion – that is not a property of RainNet itself but of its recursive application. In the context of early warning, the smoothing is particularly unfavorable since pronounced features of intense precipitation tend to get lost over longer lead times. Hence, we propose several options to address this issue in prospective research, including an adjustment of the loss function for model training, model training for longer lead times, and the prediction of threshold exceedance in terms of a binary segmentation task. Furthermore, we suggest additional input data that could help to better identify situations with imminent precipitation dynamics. The model code, pretrained weights, and training data are provided in open repositories as an input for such future studies.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 964
KW - weather
KW - models
KW - skill
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-472942
SN - 1866-8372
IS - 964
ER -
TY - JOUR
A1 - Ayzel, Georgy
A1 - Scheffer, Tobias
A1 - Heistermann, Maik
T1 - RainNet v1.0
BT - a convolutional neural network for radar-based precipitation nowcasting
JF - Geoscientific Model Development
N2 - In this study, we present RainNet, a deep convolutional neural network for radar-based precipitation nowcasting. Its design was inspired by the U-Net and SegNet families of deep learning models, which were originally designed for binary segmentation tasks. RainNet was trained to predict continuous precipitation intensities at a lead time of 5min, using several years of quality-controlled weather radar composites provided by the German Weather Service (DWD). That data set covers Germany with a spatial domain of 900km × 900km and has a resolution of 1km in space and 5min in time. Independent verification experiments were carried out on 11 summer precipitation events from 2016 to 2017. In order to achieve a lead time of 1h, a recursive approach was implemented by using RainNet predictions at 5min lead times as model inputs for longer lead times. In the verification experiments, trivial Eulerian persistence and a conventional model based on optical flow served as benchmarks. The latter is available in the rainymotion library and had previously been shown to outperform DWD's operational nowcasting model for the same set of verification events.
RainNet significantly outperforms the benchmark models at all lead times up to 60min for the routine verification metrics mean absolute error (MAE) and the critical success index (CSI) at intensity thresholds of 0.125, 1, and 5mm h⁻¹. However, rainymotion turned out to be superior in predicting the exceedance of higher intensity thresholds (here 10 and 15mm h⁻¹). The limited ability of RainNet to predict heavy rainfall intensities is an undesirable property which we attribute to a high level of spatial smoothing introduced by the model. At a lead time of 5min, an analysis of power spectral density confirmed a significant loss of spectral power at length scales of 16km and below. Obviously, RainNet had learned an optimal level of smoothing to produce a nowcast at 5min lead time. In that sense, the loss of spectral power at small scales is informative, too, as it reflects the limits of predictability as a function of spatial scale. Beyond the lead time of 5min, however, the increasing level of smoothing is a mere artifact – an analogue to numerical diffusion – that is not a property of RainNet itself but of its recursive application. In the context of early warning, the smoothing is particularly unfavorable since pronounced features of intense precipitation tend to get lost over longer lead times. Hence, we propose several options to address this issue in prospective research, including an adjustment of the loss function for model training, model training for longer lead times, and the prediction of threshold exceedance in terms of a binary segmentation task. Furthermore, we suggest additional input data that could help to better identify situations with imminent precipitation dynamics. The model code, pretrained weights, and training data are provided in open repositories as an input for such future studies.
KW - weather
KW - models
KW - skill
Y1 - 2020
U6 - https://doi.org/10.5194/gmd-13-2631-2020
SN - 1991-959X
SN - 1991-9603
VL - 13
IS - 6
SP - 2631
EP - 2644
PB - Copernicus Publ.
CY - Göttingen
ER -
TY - JOUR
A1 - Baes, Marzieh
A1 - Sobolev, Stephan
A1 - Gerya, Taras V.
A1 - Brune, Sascha
T1 - Plume-induced subduction initiation
BT - single-slab or multi-slab subduction?
JF - Geochemistry, geophysics, geosystems
N2 - Initiation of subduction following the impingement of a hot buoyant mantle plume is one of the few scenarios that allow breaking the lithosphere and recycling a stagnant lid without requiring any preexisting weak zones. Here, we investigate factors controlling the number and shape of retreating subducting slabs formed by plume-lithosphere interaction. Using 3-D thermomechanical models we show that the deformation regime, which defines formation of single-slab or multi-slab subduction, depends on several parameters such as age of oceanic lithosphere, thickness of the crust and large-scale lithospheric extension rate. Our model results indicate that on present-day Earth multi-slab plume-induced subduction is initiated only if the oceanic lithosphere is relatively young (<30-40 Myr, but >10 Myr), and the crust has a typical thickness of 8 km. In turn, development of single-slab subduction is facilitated by older lithosphere and pre-imposed extensional stresses. In early Earth, plume-lithosphere interaction could have led to formation of either episodic short-lived circular subduction when the oceanic lithosphere was young or to multi-slab subduction when the lithosphere was old.
KW - subduction zone
KW - plume
KW - numerical model
KW - singleslab
KW - multi-slab
Y1 - 2020
U6 - https://doi.org/10.1029/2019GC008663
SN - 1525-2027
VL - 21
IS - 2
PB - American Geophysical Union
CY - Washington
ER -
TY - JOUR
A1 - Baes, Marzieh
A1 - Sobolev, Stephan V.
A1 - Gerya, Taras V.
A1 - Brune, Sascha
T1 - Subduction initiation by Plume-Plateau interaction
BT - insights from numerical models
JF - Geochemistry, geophysics, geosystems
N2 - It has recently been demonstrated that the interaction of a mantle plume with sufficiently old oceanic lithosphere can initiate subduction. However, the existence of large lithospheric heterogeneities, such as a buoyant plateau, in proximity to a rising plume head may potentially hinder the formation of a new subduction zone. Here, we investigate this scenario by means of 3-D numerical thermomechanical modeling. We explore how plume-lithosphere interaction is affected by lithospheric age, relative location of plume head and plateau border, and the strength of the oceanic crust. Our numerical experiments suggest four different geodynamic regimes: (a) oceanic trench formation, (b) circular oceanic-plateau trench formation, (c) plateau trench formation, and (d) no trench formation. We show that regardless of the age and crustal strength of the oceanic lithosphere, subduction can initiate when the plume head is either below the plateau border or at a distance less than the plume radius from the plateau edge. Crustal heterogeneity facilitates subduction initiation of old oceanic lithosphere. High crustal strength hampers the formation of a new subduction zone when the plume head is located below a young lithosphere containing a thick and strong plateau. We suggest that plume-plateau interaction in the western margin of the Caribbean could have resulted in subduction initiation when the plume head impinged onto the oceanic lithosphere close to the border between plateau and oceanic crust.
KW - subduction zone
KW - plume
KW - plateau
KW - numerical modeling
KW - plume-induced
KW - subduction initiation (PISI)
Y1 - 2020
U6 - https://doi.org/10.1029/2020GC009119
SN - 1525-2027
VL - 21
IS - 8
PB - American Geophysical Union
CY - Washington
ER -
TY - GEN
A1 - Baes, Marzieh
A1 - Sobolev, Stephan Vladimir
A1 - Gerya, Taras V.
A1 - Brune, Sascha
T1 - Plume-induced subduction initiation
BT - Single-slab or multi-slab subduction?
T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - Initiation of subduction following the impingement of a hot buoyant mantle plume is one of the few scenarios that allow breaking the lithosphere and recycling a stagnant lid without requiring any preexisting weak zones. Here, we investigate factors controlling the number and shape of retreating subducting slabs formed by plume-lithosphere interaction. Using 3-D thermomechanical models we show that the deformation regime, which defines formation of single-slab or multi-slab subduction, depends on several parameters such as age of oceanic lithosphere, thickness of the crust and large-scale lithospheric extension rate. Our model results indicate that on present-day Earth multi-slab plume-induced subduction is initiated only if the oceanic lithosphere is relatively young (<30-40 Myr, but >10 Myr), and the crust has a typical thickness of 8 km. In turn, development of single-slab subduction is facilitated by older lithosphere and pre-imposed extensional stresses. In early Earth, plume-lithosphere interaction could have led to formation of either episodic short-lived circular subduction when the oceanic lithosphere was young or to multi-slab subduction when the lithosphere was old.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1167
KW - subduction zone
KW - plume
KW - numerical model
KW - singleslab
KW - multi-slab
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-522742
SN - 1866-8372
IS - 2
ER -
TY - JOUR
A1 - Bahr, André
A1 - Kolber, Gilles
A1 - Kaboth-Bahr, Stefanie
A1 - Reinhardt, Lutz
A1 - Friedrich, Oliver
A1 - Pross, Jörg
T1 - Mega-monsoon variability during the late Triassic
BT - re-assessing the role of orbital forcing in the deposition of playa sediments in the Germanic Basin
JF - Sedimentology : the journal of the International Association of Sedimentologists
N2 - The formation of the supercontinent Pangaea during the Permo-Triassic gave rise to an extreme monsoonal climate (often termed 'mega-monsoon') that has been documented by numerous palaeo-records. However, considerable debate exists about the role of orbital forcing in causing humid intervals in an otherwise arid climate. To shed new light on the forcing of monsoonal variability in subtropical Pangaea, this study focuses on sediment facies and colour variability of playa and alluvial fan deposits in an outcrop from the late Carnian (ca 225 Ma) in the southern Germanic Basin, south-western Germany. The sediments were deposited against a background of increasingly arid conditions following the humid Carnian Pluvial Event (ca 234 to 232 Ma). The ca 2 center dot 4 Myr long sedimentary succession studied shows a tripartite long-term evolution, starting with a distal mud-flat facies deposited under arid conditions. This phase was followed by a highly variable playa-lake environment that documents more humid conditions and finally a regression of the playa-lake due to a return of arid conditions. The red-green (a*) and lightness (L*) records show that this long-term variability was overprinted by alternating wet/dry cycles driven by orbital precession and ca 405 kyr eccentricity, without significant influence of obliquity. The absence of obliquity in this record indicates that high-latitude forcing played only a minor role in the southern Germanic Basin during the late Carnian. This is different from the subsequent Norian when high-latitude signals became more pronounced, potentially related to the northward drift of the Germanic Basin. The recurring pattern of pluvial events during the late Triassic demonstrates that orbital forcing, in particular eccentricity, stimulated the occurrence and intensity of wet phases. It also highlights the possibility that the Carnian Pluvial Event, although most likely triggered by enhanced volcanic activity, may also have been modified by an orbital stimulus.
KW - Carnian Pluvial Event
KW - Germanic Basin
KW - Late Triassic
KW - mega-monsoon
KW - orbital forcing
KW - playa-lake
Y1 - 2019
U6 - https://doi.org/10.1111/sed.12668
SN - 0037-0746
SN - 1365-3091
VL - 67
IS - 2
SP - 951
EP - 970
PB - Wiley-Blackwell
CY - Oxford
ER -
TY - JOUR
A1 - Balischewski, Christian
A1 - Behrens, Karsten
A1 - Zehbe, Kerstin
A1 - Günter, Christina
A1 - Mies, Stefan
A1 - Sperlich, Eric
A1 - Kelling, Alexandra
A1 - Taubert, Andreas
T1 - Ionic liquids with more than one metal
BT - optical and rlectrochemical properties versus d-block metal vombinations
JF - Chemistry - a European journal
N2 - Thirteen N-butylpyridinium salts, including three monometallic [C4Py](2)[MCl4], nine bimetallic [C4Py](2)[(M1-xMxCl4)-M-a-Cl-b] and one trimetallic compound [C4Py](2)[(M1-y-zMyMz (c) Cl4)-M-a-M-b] (M=Co, Cu, Mn; x=0.25, 0.50 or 0.75 and y=z=0.33), were synthesized and their structure and thermal and electrochemical properties were studied. All compounds are ionic liquids (ILs) with melting points between 69 and 93 degrees C. X-ray diffraction proves that all ILs are isostructural. The conductivity at room temperature is between 10(-4) and 10(-8) S cm(-1). Some Cu-based ILs reach conductivities of 10(-2) S cm(-1), which is, however, probably due to IL dec. This correlates with the optical bandgap measurements indicating the formation of large bandgap semiconductors. At elevated temperatures approaching the melting points, the conductivities reach up to 1.47x10(-1) S cm(-1) at 70 degrees C. The electrochemical stability windows of the ILs are between 2.5 and 3.0 V.
KW - bandgap
KW - electrochemistry
KW - ionic liquids
KW - metal-containing ionic
KW - liquids
KW - tetrahalido metallates
Y1 - 2020
U6 - https://doi.org/10.1002/chem.202003097
SN - 0947-6539
SN - 1521-3765
VL - 26
IS - 72
SP - 17504
EP - 17513
PB - Wiley-VCH
CY - Weinheim
ER -
TY - JOUR
A1 - Barbolini, Natasha
A1 - Woutersen, Amber
A1 - Dupont-Nivet, Guillaume
A1 - Silvestro, Daniele
A1 - Tardif-Becquet, Delphine
A1 - Coster, Pauline M. C.
A1 - Meijer, Niels
A1 - Chang, Cun
A1 - Zhang, Hou-Xi
A1 - Licht, Alexis
A1 - Rydin, Catarina
A1 - Koutsodendris, Andreas
A1 - Han, Fang
A1 - Rohrmann, Alexander
A1 - Liu, Xiang-Jun
A1 - Zhang, Y.
A1 - Donnadieu, Yannick
A1 - Fluteau, Frederic
A1 - Ladant, Jean-Baptiste
A1 - Le Hir, Guillaume
A1 - Hoorn, M. Carina
T1 - Cenozoic evolution of the steppe-desert biome in Central Asia
JF - Science Advances
N2 - The origins and development of the arid and highly seasonal steppe-desert biome in Central Asia, the largest of its kind in the world, remain largely unconstrained by existing records. It is unclear how Cenozoic climatic, geological, and biological forces, acting at diverse spatial and temporal scales, shaped Central Asian ecosystems through time. Our synthesis shows that the Central Asian steppe-desert has existed since at least Eocene times but experienced no less than two regime shifts, one at the Eocene-Oligocene Transition and one in the mid-Miocene. These shifts separated three successive "stable states," each characterized by unique floral and faunal structures. Past responses to disturbance in the Asian steppe-desert imply that modern ecosystems are unlikely to recover their present structures and diversity if forced into a new regime. This is of concern for Asian steppes today, which are being modified for human use and lost to desertification at unprecedented rates.
Y1 - 2020
U6 - https://doi.org/10.1126/sciadv.abb8227
SN - 2375-2548
VL - 6
IS - 41
PB - American Association for the Advancement of Science
CY - Washington
ER -
TY - JOUR
A1 - Baroni, Gabriele
A1 - Francke, Till
T1 - An effective strategy for combining variance- and distribution-based global sensitivity analysis
JF - Environmental modelling & software with environment data news
N2 - We present a new strategy for performing global sensitivity analysis capable to estimate main and interaction effects from a generic sampling design. The new strategy is based on a meaningful combination of varianceand distribution-based approaches. The strategy is tested on four analytic functions and on a hydrological model. Results show that the analysis is consistent with the state-of-the-art Saltelli/Jansen formula but to better quantify the interaction effect between the input factors when the output distribution is skewed. Moreover, the estimation of the sensitivity indices is much more robust requiring a smaller number of simulations runs. Specific settings and alternative methods that can be integrated in the new strategy are also discussed. Overall, the strategy is considered as a new simple and effective tool for performing global sensitivity analysis that can be easily integrated in any environmental modelling framework.
KW - global sensitivity analysis
KW - variance
KW - distribution
KW - generic sampling
KW - design
Y1 - 2020
U6 - https://doi.org/10.1016/j.envsoft.2020.104851
SN - 1364-8152
SN - 1873-6726
VL - 134
PB - Elsevier
CY - Oxford
ER -
TY - THES
A1 - Barrionuevo, Matías
T1 - The role of the upper plate in the Andean tectonic evolution (33-36°S): insights from structural geology and numerical modeling
T1 - El rol de la placa superior en la evolución tectónica andina (33-36°S): aportes desde la geología estructural y el modelado numérico
T1 - Die Rolle der oberen Platte in der tektonischen Entwicklung der Anden (33-36°S): Erkenntnisse aus der Strukturgeologie und der numerischen Modellierung
N2 - Los Andes Centrales del Sur (33-36°S) son un gran laboratorio para el estudio de los procesos de deformación orogénica, donde las condiciones de borde, como la geometría de la placa subductada, imponen un importante control sobre la deformación andina. Por otro lado, la Placa Sudamericana presenta una serie de heterogeneidades que también imparten un control sobre el modo de deformación. El objetivo de esta tesis es probar el control de este último factor sobre la construcción del sistema orogénico andino.
A partir de la integración de la información superficial y de subsuelo en el área sur (34°-36°S), se estudió la evolución de la deformación andina sobre el segmento de subducción normal. Se desarrolló un modelo estructural que evalúa el estado de esfuerzos desde el Mioceno hasta la actualidad, el rol de estructuras previas y su influencia en la migración de fluidos. Con estos datos y publicaciones previas de la zona norte del área de estudio (33°-34ºS), se realizó un modelado numérico geodinámico para probar la hipótesis del papel de las heterogeneidades de la placa superior en la evolución andina. Se utilizaron dos códigos (LAPEX-2D y ASPECT) basados en elementos finitos/diferencias finitas, que simulan el comportamiento de materiales con reologías elastoviscoplásticas bajo deformación. Los resultados del modelado sugieren que la deformación contraccional de la placa superior está significativamente controlada por la resistencia de la litósfera, que está definida por la composición de la corteza superior e inferior y por la proporción del manto litosférico, que a su vez está definida por eventos tectónicos previos. Estos eventos previos también definieron la composición de la corteza y su geometría, que es otro factor que controla la localización de la deformación. Con una composición de corteza inferior más félsica, la deformación sigue un modo de cizalla pura mientras que las composiciones más máficas provocan un modo de deformación tipo cizalla simple. Por otro lado, observamos que el espesor inicial de la litósfera controla la localización de la deformación, donde zonas con litósfera más fina es propensa a concentrar la deformación. Un límite litósfera-astenósfera asimétrico, como resultado del flujo de la cuña mantélica tiende a generar despegues vergentes al E.
N2 - The Southern Central Andes (33°-36°S) are an excellent natural laboratory to study orogenic deformation processes, where boundary conditions, such as the geometry of the subducted plate, impose an important control on the evolution of the orogen. On the other hand, the South American plate presents a series of heterogeneities that additionally impart control on the mode of deformation. This thesis aims to test the control of this last factor over the construction of the Cenozoic Andean orogenic system.
From the integration of surface and subsurface information in the southern area (34-36°S), the evolution of Andean deformation over the steeply dipping subduction segment was studied. A structural model was developed evaluating the stress state from the Miocene to the present-day and its influence in the migration of magmatic fluids and hydrocarbons. Based on these data, together with the data generated by other researchers in the northern zone of the study area (33-34°S), geodynamic numerical modeling was performed to test the hypothesis of the decisive role of upper-plate heterogeneities in the Andean evolution. Geodynamic codes (LAPEX-2D and ASPECT) which simulate the behavior of materials with elasto-visco-plastic rheologies under deformation, were used. The model results suggest that upper-plate contractional deformation is significantly controlled by the strength of the lithosphere, which is defined by the composition of the upper and lower crust, and by the proportion of lithospheric mantle, which in turn is determined by previous tectonic events. In addition, the previous regional tectono-magmatic events also defined the composition of the crust and its geometry, which is another factor that controls the localization of deformation. Accordingly, with more felsic lower crustal composition, the deformation follows a pure-shear mode, while more mafic compositions induce a simple-shear deformation mode. On the other hand, it was observed that initial lithospheric thickness may fundamentally control the location of deformation, with zones characterized by thin lithosphere are prone to concentrate it. Finally, it was found that an asymmetric lithosphere-astenosphere boundary resulting from corner flow in the mantle wedge of the eastward-directed subduction zone tends to generate east-vergent detachments.
N2 - Die südlichen Zentralanden (33°-36°S) sind eine ausgezeichnete, natürliche Forschungsumgebung zur Untersuchung gebirgsbildender Deformationsprozesse, in der Randbedingungen, wie die Geometrie der subduzierten Platte, einen starken Einfluss auf die Evolution des Gebirges besitzen. Anderseits sind die Deformationsmechanismen geprägt von der Heterogenität der Südamerikanischen Platte. In dieser Arbeit wird die Bedeutung dieses Mechanismus für die Herausbildung der Anden während des Känozoikums untersucht.
Im südlichen Teil (34-36°S), in dem die subduzierte Platte in einem steileren Winkel in den Erdmantel absinkt, wird die Entwicklung der Andendeformation mithilfe von oberflächlich aufgezeichneten und in tiefere Erdschichten reichenden Daten untersucht. Das darauf aufbauende Strukturmodell ermöglicht die Abschätzung der tektonischen Spannungen vom Miozän bis in die Neuzeit und den Einfluss der Bewegungen von magmatischen Fluiden, sowie Kohlenwasserstoffen. Auf Grundlage dieser Daten und solcher, die von Wissenschaftlern im nördlichen Bereich des Untersuchungsgebietes (33-34°S) erfasst wurden, wurde eine geodynamische, numerische Modellierung durchgeführt, um die Hypothese des Einflusses der Heterogenität der oberen Platten auf die Gebirgsbildung der Anden zu überprüfen. Die genutzte geodynamische Softwares (LAPEX-2D und ASPECT) simulieren das Verhalten von elasto-viskoplastischen Materialien, wenn diese unter Spannung stehen. Die Modellierungsergebnisse zeigen, dass die Kontraktionsprozesse hauptsächlich durch die Stärke der Lithosphäre beeinflusst werden. Diese Kenngröße wird aus der Zusammensetzung von Ober- und Unterkruste und dem Anteil des lithosphärischen Mantels, der durch vorhergehende tektonische Vorgänge überprägt ist, bestimmt. Diese räumlich begrenzten tektono-magmatischen Events definieren ebenfalls die Zusammensetzung und die Geometrie der Erdkruste, welche einen großen Einfluss auf das räumliche Auftreten von Deformationsprozessen hat. Eine eher felsische Unterkruste führt vorrangig zu pure-shear, während eine eher mafisch zusammengesetzte Unterkruste primär zu einem Deformationsmechanismus führt, der simple-shear genannt wird. Weiterhing wurde beobachtet, dass die Dicke der Lithosphäre vor der Deformation einen fundamentalen Einfluss auf die räumliche Eingrenzung von Deformation hat, wobei Regionen mit einer dünnen Lithosphärenschicht verstärkt Deformation aufweisen. Eine asymmetrische Grenzschicht zwischen Lithosphäre und Asthenosphäre ist das Resultat von Fließprozessen im Erdmantel, im Keil zwischen der obenliegenden Platte und der sich ostwärts absinkenden Subduktionszone, und verstärkt die Herausbildung von nach Osten gerichteten Abscherungen in der Erdkruste.
KW - structural geology
KW - tectonics
KW - subduction
KW - geodynamic modeling
KW - geodynamische Modellierung
KW - Strukturgeologie
KW - Subduktion
KW - Tektonik
Y1 - 2021
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515909
ER -
TY - GEN
A1 - Ben Dor, Yoav
A1 - Neugebauer, Ina
A1 - Enzel, Yehouda
A1 - Schwab, Markus J.
A1 - Tjallingii, Rik
A1 - Erel, Yigal
A1 - Brauer, Achim
T1 - Reply to comment on: Ben Dor, Yoav et al. : Varves of the Dead Sea sedimentary record. - In: Quaternary science reviews : the international multidisciplinary research and review journal. - 215 (2019), S. 173 - 184. - (ISSN: 0277-3791). - https://doi.org/10.1016/j.quascirev.2019.04.011
T2 - Quaternary science reviews : the international multidisciplinary research and review journal
N2 - In the comment on "Varves of the Dead Sea sedimentary record." Quaternary Science Reviews 215 (Ben Dor et al., 2019): 173-184. by R. Bookman, two recently published papers are suggested to prove that the interpretation of the laminated sedimentary sequence of the Dead Sea, deposited mostly during MIS2 and Holocene pluvials, as annual deposits (i.e., varves) is wrong. In the following response, we delineate several lines of evidence which coalesce to demonstrate that based on the vast majority of evidence, including some of the evidence provided in the comment itself, the interpretation of these sediments as varves is the more likely scientific conclusion. We further discuss the evidence brought up in the comment and its irrelevance and lack of robustness for addressing the question under discussion.
Y1 - 2020
U6 - https://doi.org/10.1016/j.quascirev.2019.106063
SN - 0277-3791
SN - 1873-457X
VL - 231
PB - Elsevier
CY - Amsterdam [u.a.]
ER -
TY - JOUR
A1 - Bentz, Stephan
A1 - Kwiatek, Grzegorz
A1 - Martinez-Garzon, Patricia
A1 - Bohnhoff, Marco
A1 - Dresen, Georg
T1 - Seismic moment evolution during hydraulic stimulations
JF - Geophysical research letters
N2 - Analysis of past and present stimulation projects reveals that the temporal evolution and growth of maximum observed moment magnitudes may be linked directly to the injected fluid volume and hydraulic energy. Overall evolution of seismic moment seems independent of the tectonic stress regime and is most likely governed by reservoir specific parameters, such as the preexisting structural inventory. Data suggest that magnitudes can grow either in a stable way, indicating the constant propagation of self-arrested ruptures, or unbound, for which the maximum magnitude is only limited by the size of tectonic faults and fault connectivity. Transition between the two states may occur at any time during injection or not at all. Monitoring and traffic light systems used during stimulations need to account for the possibility of unstable rupture propagation from the very beginning of injection by observing the entire seismicity evolution in near-real time and at high resolution for an immediate reaction in injection strategy.
Plain Language Summary Predicting and controlling the size of earthquakes caused by fluid injection is currently the major concern of many projects associated with geothermal energy production. Here, we analyze the magnitude and seismic moment evolution with injection parameters for prominent geothermal and scientific projects to date. Evolution of seismicity seems to be largely independent of the tectonic stress background and seemingly depends on reservoir specific characteristics. We find that the maximum observed magnitudes relate linearly to the injected volume or hydraulic energy. A linear relation suggests stable growth of induced ruptures, as predicted by current models, or rupture growth may no longer depend on the stimulated volume but on tectonics. A system may change between the two states during the course of fluid injection. Close-by and high-resolution monitoring of seismic and hydraulic parameters in near-real time may help identify these fundamental changes in ample time to change injection strategy and manage maximum magnitudes.
Y1 - 2020
U6 - https://doi.org/10.1029/2019GL086185
SN - 0094-8276
SN - 1944-8007
VL - 47
IS - 5
PB - American Geophysical Union
CY - Washington
ER -