Gpm Field Campaigns for Algorithm Physics

The Global Precipitation Mission (GPM) will employ a constellation of ~8 satellites to measure precipitation between +/-65o latitude[1]. The GPM constellation will fly microwave radiometers accompanied by a core “reference” satellite carrying a Ka-Ku band dual-frequency radar (DPR) and an improved passive microwave radiometer (GMI; frequencies 10-183 GHz). Fundamentally, the improved GPM remote sensing capability is expected to improve measurement accuracy. However, the extendedlatitudinal sampling domain of GPM necessitates the development of retrieval algorithms that can reliably estimate precipitation over a larger fraction of the earth’s land surface (in comparison to coverage of the Tropical Rainfall Measurement Mission; TRMM), and also accurately measure light precipitation (0.2 mm hr) and snowfall. The regime and process complexity (Table 1), number of parameters to be measured, and the science required to make effective use of those measurements in retrieval algorithms requires an extensive validation program. Herein we describe the physical process component of the GPM Ground Validation (GV) programoriented explicitly toward field campaign plans designed to improve and validate retrieval algorithm physics.