Quantifying snowfall scattering and microphysical properties from the Global Precipitation Mission Cold season Precipitation Experiment (GCPEx)

The scattering properties and other microphysical characteristics of snow at weather radar to millimeter wavelengths remain elusive, and thus our ability to retrieve snowfall properties such as mass, habit, and precipitation rate remain poorly constrained. Radar observations at C, X, Ku, Ka, and W band from ground based scanning radars, profiling radars, and aircraft from GCPEx, conducted in early 2012 near Barrie, Ontario, Canada, can be used to constrain the observed reflectivites in snow as well as construct dual frequency ratios (DFRs) that can be used to identify snow scattering regimes. These data can be directly matched with aircraft and ground based in situ microphysical probes, such as 2-D and bulk aircraft probes and surface disdrometers, to identify the microphysical and scattering properties of the snow to place the radar scattering regimes in context with the snow microphysical properties throughout the column of hydrometeors.

In this presentation, snow scattering regimes will be identified in GCPEx storm events using a clustering technique in a multi-frequency DFR-near Rayleigh radar reflectivity phase space using matched ground-based and aircraft-based radar data. These data will be interpreted using matched in situ disdrometer and aircraft probe microphysical data (particle size distributions, habit identification, fall speed, mass-diameter relationships) derived during the events analyzed. This database is geared towards evaluating scattering simulations and the choice of integral particle size distributions for snow precipitation retrieval algorithms for ground and spaceborne radars at relevant wavelengths. A comparison of results for different cases with different synoptic forcing will be presented.