Characterization of Snowfall Properties at High Latitude Sites through Coincident Radar, Snowflake, and Fallspeed Observations

Estimates of snowfall rate derived from radar reflectivities alone are non-unique. Different combinations of snowflake microphysical properties and particle fallspeeds can conspire to produce nearly identical snowfall rates for a given radar reflectivity signature. Such ambiguities can result in retrieval uncertainties on the order of 100-200% for individual events. Here, we use observations of snowflake particle size distribution, fallspeed, and habit from the Precipitation Imaging Package (PIP) and Multi-Angle Snow Camera (MASC) to constrain estimates of snowfall rate as derived from radar measurements. Specifically, microphysical properties derived from the PIP and MASC with uncertainties are introduced into a modified form of the optimal-estimation CloudSat snowfall algorithm (2C-SNOW-PROFILE) via the a priori guess and variance terms. Retrieval results will be presented for three distinct meteorological sites (1) the ARM NSA Barrow Climate Facility site containing a MASC and Ka-band ARM Zenith Radar, (2) the Haukeliseter Fjellstue field site in the Norwegian mountains housing a Micro Rain Radar (MRR), MASC, and PIP and (3) a Kiruna field site located in Arctic Sweden deploying a MRR, PIP, and MASC. Retrieved snowfall rates will be compared with snow gauge observations to evaluate retrieval scheme performance. These analyses, as well as descriptions of snow particle size distributions, habits, and fallspeeds, will be presented as a function of storm event type and meteorological conditions.