Towards Development of an Operational Snowfall Product for the North Slope Alaska ARM Climate Facility Sites

Description

Cloud and precipitation processes help regulate many high-latitude climate feedback mechanisms. Understanding the role of clouds and precipitation in these feedbacks, however, depends implicitly on a rigorous characterization of the microphysical structure of high latitude precipitating cloud systems. Here, we present retrieval methodology and sample results for a new snowfall product based upon the instrumentation of the North Slope Alaska ARM Climate Facility Sites. The retrieval scheme is founded primarily upon Ka-band ARM Zenith Radar (KAZR) observations and is modified from the optimal-estimation CloudSat snowfall algorithm (2C-SNOW-PROFILE). Specifically, the scheme returns estimates of surface snowfall rate and vertical profiles of snow water content and size distribution parameters at a one minute time resolution. The scheme also provides uncertainties for each of these parameters along with diagnostics suggesting confidence in returned values. For results, we present bulk statistics for snowfall products for a three-year period from 2014-2016 for the Barrow site. Retrieved snowfall values were evaluated relative to nearby National Weather Service snow gauge observations. Uncertainties in snowfall products derived from the KAZR measurements alone can be on the order of 100-200% for individual events. As such, we also explored the use of snowflake microphysical observations from the Multi-Angle Snow Camera (MASC) to constrain the snowfall estimates derived from KAZR reflectivities. It is expected that the snow products generated through this work will be useful for cloud and precipitation process studies for the ASR community.