ICESat-2 Observations of Blowing Snow Over Arctic Sea Ice During the 2019–2020 MOSAiC Expedition

Abstract

Blowing snow plays a key role in the surface mass and energy budgets of polar regions and can be a significant source of water vapor to the atmosphere. In this study, we optimize the algorithm for detecting blowing snow from NASA's Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) satellite for use over Arctic sea ice. We analyze six months (November 2019 through April 2020) of observations from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign together with 612 nearly coincident (within 100 km) ICESat-2 overpasses to evaluate the ICESat-2 detection algorithm and inferred blowing snow properties. Both ICESat-2 and MOSAiC suggest a blowing snow occurrence frequency of 17% during the period of study. Blowing snow particle number and inferred from ICESat-2 show broad agreement with in situ observations made at 10 m above the surface during MOSAiC but are often well below observations made at 8 cm. Within a 100 km radius around the MOSAiC observatory, we find a cumulative blowing snow sublimation of 2.38 cm snow-water-equivalent (SWE), comparable to MOSAiC (2.56 cm SWE) and SnowModel-LG (2.35 cm SWE) estimates. This suggests that blowing snow sublimation removed 22%–33% of snowfall during MOSAiC. Across the central Arctic, ICESat-2 and SnowModel-LG indicate blowing snow occurrence frequencies as high as 18%–25%, with cumulative blowing snow sublimation fluxes (1.74–1.79 cm SWE) removing 16%–17% of snowfall. These findings highlight the importance of blowing snow sublimation for the Arctic snow on sea ice budget.