Verification of GPCP-1DD global satellite precipitation products using MAP surface observations

Abstract

Daily satellite precipitation estimates have become available for the first time by the Global Precipitation Climatology Project. The experimental version of the GPCP-1DD product, recently launched and available from NASA, provides the research community with 1 degree daily precipitation fields exclusively computed from satellite measurements. These comprise IR estimates from geostationary satellites and SSM/I data in the tropics as well as TOVS data from polar orbiting satellites at higher latitudes. The purpose of the present study is to verify the TOVS based GPCP-1DD rain rates over Central Europe with the surface precipitation measured with the dense rain gauge network operated during The Mesoscale Alpine Programme (MAP). 3 100 high quality daily rain gauge measurements during June/July 1997 have been objectively analyzed on the grid of the GPCP-1DD products. Verification results are given here in terms of difference fields (mean error=−0.59 mm/day), correlation coefficients (mean monthly value =0.57) as well as accuracy scores (probability of detection=0.6, false alarm ratio=0.2) and skill scores (true skill statistics=0.36). These scores are slightly inferior than those known from NWP model verifications.