Snow cover on Arctic sea ice in observations and an Earth System Model

Spring snow depth on Arctic sea ice is assessed in observations and an Earth System Model. In both, snow depth is mainly driven by the ice type on which the snow lies. Snow depths on multiyear ice are approximately double snow depths on first-year ice. In the model spring snow depths are greater on multiyear ice compared to first-year ice primarily because multiyear ice begins to accumulate snow earlier in the fall but also due to snow cover survival through the summer on multiyear ice. The model simulates a decline in spring snow depth driven mainly by a transition from a multiyear to first-year ice regime throughout the Arctic. Agreement in the loss of multiyear ice in the model with estimates from observations suggests that declining snow depths in observations mainly result from the loss of multiyear sea ice.