Improve iLOVECLIM (version 1.1) with a multi-layer snow model: surface mass balance evolution during the Last Interglacial

Abstract. During the Quaternary, ice sheets experienced several retreat-advanced cycles, strongly influencing climate patterns. In order to properly simulate these phenomena, it is preferable to use physics-based models instead of parameterizations to estimate surface mass balance (SMB) which has a strong influence on the ice sheet evolution. To further investigate the potential of these SMB models, this work evaluates BESSI (BErgen Snow Simulator), a multi-layer snow model with high computational efficiency, as an alternative to providing SMB for paleo studies. First, we validate the snow model using the regional climate model MAR (Modèle Atmosphérique Régional) as forcing and reference for the present-day climate over Greenland and Antarctic Ice Sheets. The evolution of SMB over the Last Interglacial period (LIG) (130–116 kaBP) is computed by forcing BESSI with transient climate forcing obtained from an Earth system model iLOVECLIM for both ice sheets. For present-day climate conditions, BESSI exhibits good performance compared to MAR despite a much simpler model set-up. The model also captures well the variation of SMB and its components during the LIG. Compared to the current simple melt estimation scheme of iLOVECLIM (ITM), BESSI is able to capture different SMB patterns for two particular ice sheet climate conditions thanks to its higher physical constraints while ITM displays a strong sensitivity to its parameters and input fields (temperature). The findings suggest that BESSI can provide more reliable SMB estimations for the iLOVECLIM framework to improve the model simulations of the ice sheet evolution and interactions with climate.