Validation of Satellite Rainfall Products over Africa and S. America

Satellite rainfall estimates are being used widely in place of gauge observations or to supplement gauge observations. Rigorous validation is required in order to have some level of confidence in using the satellite products for different applications. Some global and regional validations have been done for different satellite rain products. In many parts of Africa and South America, where these products are arguably needed most, there has been very little validation work. The few validations works over have mainly been limited to few products, particularly to monthly estimates at a spatial resolution of 2.5o x 2.5o lat/long. Here different satellite rainfall products are evaluated over Africa and South America at different spatial and temporal scales. The validation is done for three groups of products. The first group has low spatial (2.5o) and temporal (monthly) resolutions. These include Global Precipitation Climatology (GPCP) Multi-satellites (GPCP-MS), GPCP Satellite and Gauge (GPCP-SG), National Oceanographic and Atmospheric Administration-Climate Prediction Centre (NOAA-CPC) Merged Analysis (CMAP), and the Tropical Rainfall Measuring Mission (TRMM) combined ‘TRMM and Other Sources' (3B43) products. TRMM-3B43 has higher spatial resolution (0.25o), but has been remapped to 2.5o in order to compare it with the other products. The second group consists of products with high spatial (0.1o to 1o) and temporal (three-hourly to 10-daily) resolutions. These products include NOAA-CPC African Rainfall Estimation Algorithm (RFE), NOAA-CPC African Rainfall Climatology (ARC), GPCP one-degree daily (1DD), the ‘TRMM and Other Satellites' product (3B42), TAMSAT (Tropical Applications of Meteorology using Satellite data), and a relatively new product from NOAA-CPC named the CPC morphing technique (CMORPH). These products are evaluated at 10-daily temporal and 1o spatial scales. The third group, consisting of RFE, TRMM-3B42, CMORPH, PERSIANN, and the Naval Research Laboratory's blended product, are evaluates at daily time scale and spatial resolution of 0.25o.