NASA GPM/PMM Participation in the Canadian CloudSat/Calipso Validation Project (C3VP): Physical process studies in snow

The NASA Global Precipitation Measurement mission (GPM) algorithm development and ground validation teams are in great need of pre-GPM-launch data sets for developing space-based snowfall detection and estimation algorithms. These data sets are needed to (1) develop and validate physical models that convert the physical characteristics of single snowflakes (shape, size distribution, density, ice-air-water ratio) to their radiative properties (asymmetry factor, absorption, scattering, and backscattering coefficients); and (2) relate the bulk layer radiative properties to calculated and observed passive microwave radiances and radar reflectivities. Accordingly, components of NASA GPM ground validation and Precipitation Measurement Mission (PMM) science teams participated in the C3VP field campaign held near Barrie, Ontario, Canada, during the winter of 2006-2007. In particular, GPM/PMM supported deployment of the UMASS Advanced Multi-Frequency Radar (Ka, Ku, W bands), CSU 2D Video Disdrometer, NASA Parsivel disdrometers, and NASA snow video imager. This suite of instrumentation operated under a much broader C3VP instrument umbrella which also included the King City C-band dual-polarimetric radar, the NRC Convair 580 aircraft and surface meteorological instrumentation. Collectively, numerous snow events including both synoptically-forced and lake effect snow bands were successfully sampled in a coordinated fashion by C3VP airborne and ground-based instrumentation. It is anticipated that subsequent analysis of these datasets will provide at least one of several ground-based physical process validation data sets around which snowfall models and retrieval algorithms can be further developed and tested. This study will present an overview of the C3VP experiment, intensive radar operations period, and preliminary precipitation science-related results.