TY - JOUR A1 - Winkelmann, Ricarda A1 - Martin, Maria A. A1 - Haseloff, Monika A1 - Albrecht, Torsten A1 - Bueler, Ed A1 - Khroulev, C. A1 - Levermann, Anders T1 - The Potsdam parallel ice sheet model (PISM-PIK) - Part 1: Model description JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union N2 - We present the Potsdam Parallel Ice Sheet Model (PISM-PIK), developed at the Potsdam Institute for Climate Impact Research to be used for simulations of large-scale ice sheet-shelf systems. It is derived from the Parallel Ice Sheet Model (Bueler and Brown, 2009). Velocities are calculated by superposition of two shallow stress balance approximations within the entire ice covered region: the shallow ice approximation (SIA) is dominant in grounded regions and accounts for shear deformation parallel to the geoid. The plug-flow type shallow shelf approximation (SSA) dominates the velocity field in ice shelf regions and serves as a basal sliding velocity in grounded regions. Ice streams can be identified diagnostically as regions with a significant contribution of membrane stresses to the local momentum balance. All lateral boundaries in PISM-PIK are free to evolve, including the grounding line and ice fronts. Ice shelf margins in particular are modeled using Neumann boundary conditions for the SSA equations, reflecting a hydrostatic stress imbalance along the vertical calving face. The ice front position is modeled using a subgrid-scale representation of calving front motion (Albrecht et al., 2011) and a physically-motivated calving law based on horizontal spreading rates. The model is tested in experiments from the Marine Ice Sheet Model Intercomparison Project (MISMIP). A dynamic equilibrium simulation of Antarctica under present-day conditions is presented in Martin et al. (2011). Y1 - 2011 U6 - https://doi.org/10.5194/tc-5-715-2011 SN - 1994-0416 VL - 5 IS - 3 SP - 715 EP - 726 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Nowicki, Sophie A1 - Bindschadler, Robert A. A1 - Abe-Ouchi, Ayako A1 - Aschwanden, Andy A1 - Bueler, Ed A1 - Choi, Hyeungu A1 - Fastook, Jim A1 - Granzow, Glen A1 - Greve, Ralf A1 - Gutowski, Gail A1 - Herzfeld, Ute A1 - Jackson, Charles A1 - Johnson, Jesse A1 - Khroulev, Constantine A1 - Larour, Eric A1 - Levermann, Anders A1 - Lipscomb, William H. A1 - Martin, Maria A. A1 - Morlighem, Mathieu A1 - Parizek, Byron R. A1 - Pollard, David A1 - Price, Stephen F. A1 - Ren, Diandong A1 - Rignot, Eric A1 - Saito, Fuyuki A1 - Sato, Tatsuru A1 - Seddik, Hakime A1 - Seroussi, Helene A1 - Takahashi, Kunio A1 - Walker, Ryan A1 - Wang, Wei Li T1 - Insights into spatial sensitivities of ice mass response to environmental change from the SeaRISE ice sheet modeling project II Greenland JF - Journal of geophysical research : Earth surface N2 - The Sea-level Response to Ice Sheet Evolution (SeaRISE) effort explores the sensitivity of the current generation of ice sheet models to external forcing to gain insight into the potential future contribution to sea level from the Greenland and Antarctic ice sheets. All participating models simulated the ice sheet response to three types of external forcings: a change in oceanic condition, a warmer atmospheric environment, and enhanced basal lubrication. Here an analysis of the spatial response of the Greenland ice sheet is presented, and the impact of model physics and spin-up on the projections is explored. Although the modeled responses are not always homogeneous, consistent spatial trends emerge from the ensemble analysis, indicating distinct vulnerabilities of the Greenland ice sheet. There are clear response patterns associated with each forcing, and a similar mass loss at the full ice sheet scale will result in different mass losses at the regional scale, as well as distinct thickness changes over the ice sheet. All forcings lead to an increased mass loss for the coming centuries, with increased basal lubrication and warmer ocean conditions affecting mainly outlet glaciers, while the impacts of atmospheric forcings affect the whole ice sheet. KW - Greenland KW - ice-sheet KW - sea-level KW - model KW - ensemble Y1 - 2013 U6 - https://doi.org/10.1002/jgrf.20076 SN - 2169-9003 VL - 118 IS - 2 SP - 1025 EP - 1044 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Martin, Maria A. A1 - Winkelmann, Ricarda A1 - Haseloff, M. A1 - Albrecht, Tanja A1 - Bueler, Ed A1 - Khroulev, C. A1 - Levermann, Anders T1 - The Potsdam parallel ice sheet model (PISM-PIK) - Part 2: Dynamic equilibrium simulation of the Antarctic ice sheet JF - The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union N2 - We present a dynamic equilibrium simulation of the ice sheet-shelf system on Antarctica with the Potsdam Parallel Ice Sheet Model (PISM-PIK). The simulation is initialized with present-day conditions for bed topography and ice thickness and then run to steady state with constant present-day surface mass balance. Surface temperature and sub-shelf basal melt distribution are parameterized. Grounding lines and calving fronts are free to evolve, and their modeled equilibrium state is compared to observational data. A physically-motivated calving law based on horizontal spreading rates allows for realistic calving fronts for various types of shelves. Steady-state dynamics including surface velocity and ice flux are analyzed for whole Antarctica and the Ronne-Filchner and Ross ice shelf areas in particular. The results show that the different flow regimes in sheet and shelves, and the transition zone between them, are captured reasonably well, supporting the approach of superposition of SIA and SSA for the representation of fast motion of grounded ice. This approach also leads to a natural emergence of sliding-dominated flow in stream-like features in this new 3-D marine ice sheet model. Y1 - 2011 U6 - https://doi.org/10.5194/tc-5-727-2011 SN - 1994-0416 VL - 5 IS - 3 SP - 727 EP - 740 PB - Copernicus CY - Göttingen ER -