Sensitivity of a Greenland ice sheet model to atmospheric forcing fields
- 1UJF – Grenoble 1/CNRS, Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE) UMR 5183, Grenoble, 38041, France
- 2Laboratoire des Sciences du Climat et de l'Environnement (LSCE)/IPSL, CEA-CNRS-UVSQ, UMR 8212, 91191 Gif-sur-Yvette, France
- 3Département de Géographie, Université de Liège, Liège, Belgium
- 4CNRM-GAME, URA CNRS-Météo-France 1357, Toulouse, France
- 5Center for Ice and Climate, Niels Bohr Institute, Copenhagen, Denmark
- *now at: Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
- **now at: GeoBiosphere Science Centre, Quaternary Sciences, Lund University, Sölvegatan 12, 223 62 Lund, Sweden
Abstract. Predicting the climate for the future and how it will impact ice sheet evolution requires coupling ice sheet models with climate models. However, before we attempt to develop a realistic coupled setup, we propose, in this study, to first analyse the impact of a model simulated climate on an ice sheet. We undertake this exercise for a set of regional and global climate models. Modelled near surface air temperature and precipitation are provided as upper boundary conditions to the GRISLI (GRenoble Ice Shelf and Land Ice model) hybrid ice sheet model (ISM) in its Greenland configuration.
After 20 kyrs of simulation, the resulting ice sheets highlight the differences between the climate models. While modelled ice sheet sizes are generally comparable to the observed one, there are considerable deviations among the ice sheets on regional scales. These deviations can be explained by biases in temperature and precipitation near the coast. This is especially true in the case of global models. But the deviations between the climate models are also due to the differences in the atmospheric general circulation. To account for these differences in the context of coupling ice sheet models with climate models, we conclude that appropriate downscaling methods will be needed. In some cases, systematic corrections of the climatic variables at the interface may be required to obtain realistic results for the Greenland ice sheet (GIS).