Validation of CMORPH and TRMM satellite rainfall algorithms for Central America

The NOAA Climate Prediction Center (CPC) provides Weekly Weather Hazards Assessments for Central America in support of humanitarian efforts by the US Agency for International Development. One major component of these Weather Hazards Assessments is the satellite derived precipitation estimates that can lend insight to drought and flood threats that may affect food/water supply and distribution that could lead to food insecurities and famine. The CPC Morphing (CMORPH) technique and NASA's TRMM technique are the satellite derived products used at the CPC for rainfall estimation in Central America. The CMORPH, at resolutions of 8km and 25km, and the TRMM, at a resolution of 25km, have been validated using point-to-grid box comparisons by utilizing rainfall data from Global Telecommunication System (GTS) stations in Central America and other independent stations for Guatemala. The comparisons are done on a daily basis for the rainy seasons (May through November) of 2003 and 2004. The objective of the validation is to assess the accuracy to which the readily used satellite derived precipitation products estimate precipitation events (both small and large-scale) in different locations (coastal, mountainous, and inland) in Central America. Results indicate that all satellite products in all locations increasingly underestimate rainfall events as the events get larger. In addition, all satellite products underestimate rainfall events in coastal regions of Central America, more so than rainfall events in non-coastal locations.