Hydrometeor Classifications of Snow using Polarimetric Radar and In Situ Observations

The 20-21 November 2010 snow event near Grand Forks, North Dakota, is studied using the University of North Dakota (UND) Citation Research Aircraft and three different radars: the Doppler on Wheels (DOW) polarimetric radar, the University of North Dakota (UND) polarimetric radar, and the Mayville (KMVX) radar. The Citation Research Aircraft's Two Dimensional Cloud Imaging Probe (2DC) provides shadow images of the snow crystals that are processed to produce size distributions and particle shape/type. Using a hydrometeor classification algorithm (HCA) that uses polarimetric radar variables as input, snow type is identified (wet snow, dry snow, and ice crystals) and compared to the 2DP shadow images. The HCA uses fuzzy logic to determine the probability of species being present, given the radar observables. Particular attention is given to times when the aircraft is passing between two HCA-identified crystal type regions. The 20-21 November 2010 observations were collected during the larger field campaign called “SNOwD UNDER” (Student Nowcasting and Observations with the DOW at UND: Education through Research). Funding for collecting observations during SNOwD UNDER was provided by the Center for Severe Weather Research, the UND Dept. of Atmos. Sci., and UTC Aerospace Systems (formerly Goodrich Corporation). Analysis funding was provided by North Dakota EPSCoR.