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 - 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 - BOOK ED - Turner, Bryan S. ED - Wolf, Hannah ED - Fitzi, Gregor ED - Mackert, Jürgen T1 - Theories and concepts T3 - Urban change and citizenship in times of crisis N2 - Urban Change and Citizenship in Times of Crisis addresses the fact that in the beginning of the twenty-first century the majority of the world’s population is urbanised, a social fact that has turned cities more than ever into focal sites of social change. Multiple economic and political strategies, employed by a variety of individual and collective actors, on a number of scales, constitute cities as contested spaces that hold opportunities as well as restrictions for their inhabitants. While cities and urban spaces have long been of central concern for the social sciences, today, classical sociological questions about the city acquire new meaning: Can cities be spaces of emancipation, or does life in the modern city entail a corrosion of citizenship rights? Is the city the focus of societal transformation processes, or do urban environments lose importance in shaping social reality and economic relationships? Furthermore, new questions urgently need to be asked: What is the impact of different historical phenomena such as neo-liberal restructuring, financial and economic crises, or migration flows, as well as their respective counter-movements, on the structure of contemporary cities and on the citizenship rights of city inhabitants? The three volumes address such crucial questions thereby opening up new spaces of debate on both the city and new developments of urbanism. The contributions to Theories and Concepts offer new theoretical reflections on the city in a philosophical and historical perspective as well as fresh empirical analyses of social life in urban contexts. Chapters not only critically revisit classical and modern philosophical considerations about the nature of cities but no less discuss normative philosophical reflections of urban life and the role of religion in historical processes of the emergence of cities. Composed around the question whether there can be such a thing as a ‘successful city’, this volume addresses issues of urban political subjectivities by considering the city’s role in historical processes of emancipation, the fight for citizenship rights, and today’s challenges and opportunities with regard to promoting social justice, integration, and diversity. Consequentially, theory-driven empirical analyses offer new insight into ways of solving problems in urban contexts and a genuine approach to analyse the Social Quality in cities. Y1 - 2020 SN - 978-0-367-20562-1 SN - 978-0-429-26226-5 U6 - https://doi.org/10.4324/9780429262265 VL - 1 PB - Routledge CY - London ER -