Ground validation of TRMM and AMSU microwave precipitation estimates

Global rain gauge data were used to validate the instantaneous and 3-hourly TRMM TMI and AMSU microwave rainfall products for a two-year period from January 2001 to December 2002. In the comparison of instantaneous rainfall products, all satellite data were aggregated to a 0.1°×0.1° grid with gauge location at the grid center and compared to the 60-minute gauge rain. The biases against gauge rain are +15% and -20% for TMI and AMSU land/coastal rain estimates, respectively. The gauge data from ocean area in this study were only from Kwajalein, The biases as compared to the Kwajalein gauge data are +12% and +65% for TMI and AMSU ocean rain estimates respectively. The correlation is about 0.56 between TMI and gauge data and about 0.50 between AMSU and gauge data.