Polarimetric Radar Evalutation of a Hygroscropic Seeding Study in Eastern North Dakota

The Polarimetric Cloud Analysis and Seeding Test (POLCAST) is an ongoing field program with the goal of improving the understanding of the impact of hygroscopic cloud seeding at cloud base on continental convective clouds. The study has focused on sampling convective clouds observed in eastern North Dakota. The radar evaluation studies targeted convective clouds to determine if identifiable hygroscopic seeding signatures can be observed in polarimetric radar fields. A randomized (seed or no seed) targeting field program has been conducted for three summer convective seasons (June-July 2008, and June-July 2010, June-August 2012). The evaluation examines polarimetric radar data collected by the UND C-Band Polarimetric Doppler Weather Radar (NorthPol). A total of 44 cases have been collected in the three field programs. Polarimetric derived hydrometeor distributions were generated for each case using the NCAR hydrometeor identification (HID) algorithm tuned for C-band observations. The hydrometeor distributions were stratified by seed and no-seeded cases and statistical evaluation has been conducted to examine if hydrometeor distributions are statistically different between seed and no-seed chases. This presentation gives a brief description of the field campaign, an overview of the methodology, and summary of results.