Reese, Ronja, Albrecht, Torsten, Mengel, Matthias, Asay-Davis, Xylar and Winkelmann, Ricarda (2018) Antarctic sub-shelf melt rates via PICO. The Cryosphere, 12 (6). pp. 1969-1985. ISSN 1994-0424
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Abstract
Ocean-induced melting below ice shelves is one of the dominant drivers for mass loss from the Antarctic Ice Sheet at present. An appropriate representation of sub-shelf melt rates is therefore essential for model simulations of marine-based ice sheet evolution. Continental-scale ice sheet models often rely on simple melt-parameterizations, in particular for long-term simulations, when fully coupled ice–ocean interaction becomes computationally too expensive. Such parameterizations can account for the influence of the local depth of the ice-shelf draft or its slope on melting. However, they do not capture the effect of ocean circulation underneath the ice shelf. Here we present the Potsdam Ice-shelf Cavity mOdel (PICO), which simulates the vertical overturning circulation in ice-shelf cavities and thus enables the computation of sub-shelf melt rates consistent with this circulation. PICO is based on an ocean box model that coarsely resolves ice shelf cavities and uses a boundary layer melt formulation. We implement it as a module of the Parallel Ice Sheet Model (PISM) and evaluate its performance under present-day conditions of the Southern Ocean. We identify a set of parameters that yield two-dimensional melt rate fields that qualitatively reproduce the typical pattern of comparably high melting near the grounding line and lower melting or refreezing towards the calving front. PICO captures the wide range of melt rates observed for Antarctic ice shelves, with an average of about 0.1 m a−1 for cold sub-shelf cavities, for example, underneath Ross or Ronne ice shelves, to 16 m a−1 for warm cavities such as in the Amundsen Sea region. This makes PICO a computationally feasible and more physical alternative to melt parameterizations purely based on ice draft geometry.
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| Additional Information: | Funding information: Development of PISM is supported by NASA grant NNX17AG65G and NSF grants PLR-1603799 and PLR-1644277. Torsten Albrecht was supported by DFG priority program SPP 1158, project numbers LE1448/6-1 and LE1448/7-1. Matthias Mengel was supported by the AXA Research Fund. Ronja Reese was supported by the German Academic National Foundation, the postgraduate scholarship programme of the state of Brandenburg and the Evangelisches Studienwerk Villigst. The project is further supported by the German Climate Modeling Initiative (PalMod) and the Leibniz project DominoES. Xylar Asay-Davis was supported by the US Department of Energy, Office of Science, Office of Biological and Environmental Research under award no. DE-SC0013038. The authors gratefully acknowledge the European Regional Development Fund (ERDF), the German Federal Ministry of Education and Research and the Land Brandenburg for supporting this project by providing resources on the high performance computer system at the Potsdam Institute for Climate Impact Research. |
| Subjects: | F700 Ocean Sciences F800 Physical and Terrestrial Geographical and Environmental Sciences F900 Others in Physical Sciences |
| Department: | Faculties > Engineering and Environment > Geography and Environmental Sciences |
| Depositing User: | Rachel Branson |
| Date Deposited: | 23 Nov 2021 11:15 |
| Last Modified: | 23 Nov 2021 11:15 |
| URI: | http://nrl.northumbria.ac.uk/id/eprint/47814 |
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