Polarimetric Radar Analysis of a Winter Cyclone Producing Mixed Precipitation

Raquel Evaristo, Adam Stepanek, Jennifer Schuller, Amanda Terborg, Kevin Deitsch, Jaclyn Ritzman, Chris Shuma, and Ian Lee
Valparaiso University

On 8 and 9 December 2009, a low pressure system approached the Great Lakes from the southwest and produced mixed phase precipitation at the surface in Valparaiso, Indiana.  Valparaiso University students and staff launched a sequence of radiosondes to document the progression of the system. One radiosonde was launched just before the arrival of the system, at approximately 2000 UTC on 8 December, and a second radiosonde launch was conducted shortly after the precipitation started, at approximately 0000 UTC on 9 December. Throughout the afternoon and evening hours, surface observations of the precipitation type were documented.  In addition, the C-band polarimetric radar located on the campus of Valparaiso University was gathering data starting at approximately 2230 UTC.

Horizontal and vertical cross-sections of the polarimetric radar variables are compared to the surface observations and the radiosonde data. This helps to verify the consistency of the radar data. Afterwards, a hydrometeor classification algorithm is applied to the radar data and again the results are compared to the surface observations. This step is important for the validation of the classification algorithm.