The Arctic Ocean snow mass budget

A two-dimensional (X-Z) numerical model specifically designed for sea ice environments is presented. This new model is used to quantify the snow mass lost due to blowing snow into leads, blowing snow sublimation and the effects of snow redistribution in the presence of surface irregularities (e.g., pressure ridges and snowdrifts) on the ocean-atmosphere heat fluxes. Results show that the percentage of blowing snow lost into open waters (i.e. the lead trap efficiency) typically reaches 80%. The trap efficiency of leads increases with fetch over open waters, decreases as the upwind fetch over sea ice expands, and diminishes as wind speeds and friction velocities are enhanced. Results from the time evolution of a snowdrift show that considerable snowcover heterogeneity arises due to interactions between winds and the surface; however the ocean-atmosphere heat fluxes increase only by 2% over 20-m length scales when compared with the case where no snow redistribution is taken into account. Based on the modeling results, 9.7% of the annual snowfall is removed by blowing snow sublimation and 4.6% by transport into leads, for a total of 14.3%. This implies that snow redistribution by wind constitutes the third largest sink term in the snow mass budget of the Arctic Ocean after surface sublimation and melt.