KAZR-CloudSat analysis of snowing clouds at the North Slope of Alaska: implications of the satellite radar blind zone

Studies have indicated regional differences between shallow and deep snowfall regimes in the mid- and high-latitudes, such as seasonal variability and response to environmental conditions. Shallow precipitating clouds are prevalent throughout the high-latitude regions. However, it is difficult to observe shallow snowfall due to the satellite radar blind zone, where currently deployed satellite radar observations in the lowest ~1-2 km of the atmosphere are obscured due to ground clutter. Because of the satellite radar blind zone, these observations underestimate snowfall accumulation from shallow clouds and may incorrectly flag snow virga as snowfall at the surface. This study investigates snowfall regimes using observations from ground-based and satellite radar observations. Ground-based radar observations are from the Ka-band ARM Zenith Radar (KAZR) 2011-2021 at the Department of Energy Atmospheric Radiation Measurement (ARM) North Slope of Alaska atmospheric observatory located in Utqiaġvik, Alaska. Collocated satellite radar observations are from the CloudSat Cloud Profiling Radar (CPR). Snowfall events are identified in the KAZR and are separated into snowing and snow virga regimes. The snowing regimes are further separated by deep and shallow cloud top heights (CTHs; CTH > 3 km AGL and CTH < 3 km AGL, respectively). The results reveal implications and challenges for satellite radar detection of snowfall near the surface, and insights for future satellite radar missions.