Radar‐Derived Snowfall Microphysical Properties at Davis, Antarctica.

Antarctic precipitation remains poorly characterized and understood, especially within the boundary layer. This is due in part to a still‐limited amount of surface‐based remote sensing observations. A suite of cloud and precipitation remote‐sensing instruments including a W‐band cloud radar and a K‐band Micro Rain Radar (MRR) were used to characterize snowfall over Davis (69°S, 78°E). Surface snowfall events occurred when boundary layer wind speeds were weaker, temperatures were warmer, and relative humidity over ice higher than when virga were present. The presence of virga is associated with Föhn winds due to the location of Davis in the lee of an ice ridgeline. Dual wavelength ratio values from the summer indicate particle aggregation at temperatures of −14° to −10°C, consistent with observations made elsewhere, including in the Arctic. Riming frequency increases for temperatures above −10°C and reaches 6.5% at −3°C. No temperature dependence of rime mass fraction was found. Sublimation of snowfall mass aloft was 50% between the snow peak at 1.2 km and 205 m altitude, which occurs within CloudSat's "blind zone." Given the common prevailing wind direction and numerous ice ridgelines along much of the East Antarctic coastline, these Davis results can be used as a basis to further understand snowfall across the Antarctic region. Plain Language Summary: We investigate the vertical structure of snowfall above a coastal Antarctic site during summer and winter using a variety of remote‐sensing instruments. The amount of snowfall that reaches near the ground is influenced by the meteorological conditions present around Davis. During strong north‐easterly winds, air passes over an upwind ice ridgeline, warming on its descent into Davis. This warm air sublimates 50% of the snowfall within the atmospheric boundary layer, meaning that only ice virga are detected by our radars. Within the snow‐bearing clouds, we found the same microphysical processes occur above coastal Antarctica as elsewhere on the Earth, in particular the temperatures at which snow particles begin to clump together. Detailed studies of the vertical structure of snowfall, such as this one, will help scientists understand the regional effects of topography and meteorology on surface snowfall, and relate what satellites observe with measurements made at or near the surface. Key Points: Particle aggregation over Davis during summer occurs at similar temperatures as in the ArcticRiming during summer occurs at temperatures above −10°C, but no temperature dependence on rime mass fraction is foundSnowfall sublimation of 50% occurs below the snow peak at 1.2 km, which is inside CloudSat's "blind zone" and is due to Föhn winds [ABSTRACT FROM AUTHOR]