1. Objective: Validate GPM Drop Size Distribution Retrievals • Drop size distributions (DSD) are critical to GPM DPR-based rainfall retrievals. • NASA GPM Science Requirements stipulate that the GPM Core observatory radar estimation of Dm shall be within +/0.5 mm of GV. • GV translates disdrometer measurements to polarimetric radar-based DSD and precipitation type retrievals (e.g., convective vs. stratiform) for coincident match-up to GPM core overpasses. • How well do we meet the requirement across product versions, rain types (e.g., C/S partitioning), and rain rates (heavy, light) and is behavior physically and internally consistent? *Contact: walt.petersen@nasa.gov

As part of the NASA tropical rainfall measuring mission ground validation (TRMM-GV) program, a field campaign was conducted in Florida Keys during August-September 2002. The purpose of the field campaign was to study the characteristics of rainfall over the Florida Keys, utilizing Key West WSR-88D, NASA's s-band polarimetric radar (NPOL), and a network of rain gauges and disdrometers. This study focuses on the performance of the rain gauges and disdrometers and its impact on the radar rainfall algorithms.