The influence of snow on sea ice as assessed from simulations of CESM2

Abstract

We assess the influence of snow on sea ice in experiments using the Community Earth System Model, version 2 for a pre-industrial and a 2xCO2 climate state. In the pre-industrial climate, we find that increasing simulated snow accumulation on sea ice results in thicker sea ice and a cooler climate in both hemispheres. The sea ice mass budget response differs fundamentally between the two hemispheres. In the Arctic, increasing snow results in a decrease in both sea ice growth and sea ice melt due to the snow’s impact on conductive heat transfer and albedo, respectively. This leads to a reduced amplitude in the annual cycle of ice thickness. In the Antarctic, with increasing snow, ice growth increases due to snow-ice formation and is balanced by larger basal ice melt. In the warmer 2xCO2 climate, the Arctic sea ice sensitivity to snow depth is small and reduced relative to that of the pre-industrial climate. Whereas, in the Antarctic, the sensitivity to snow on sea ice in the 2xCO2 climate is qualitatively similar to the sensitivity in the pre-industrial climate. These results underscore the importance of accurately representing snow accumulation on sea ice in coupled earth system models, due to its impact on a number of competing processes and feedbacks.