Challenges and proposed solutions for validation of spaceborne rain rate estimates

The method of using probability density functions (PDF) of rain rates (R) for validation of rain rate estimates from different sensors at different scales is investigated. Distributions of rain volume by R as derived from the TRMM spaceborne radar are compared with those based on collocated data from ground-based radar observations. The uncertainties in the ground-based radar PDF are reduced upon adjustment to the gauge-based R distribution. This paper discusses how to better represent the actual R distribution at the scale of a radar pixel using ground observations. Utilizing super dense gauge networks will further reduce the uncertainties, and will permit better evaluation of instantaneous rainfall products based on ground and space observations.