Evaluation of remote sensing precipitation estimates over Saudi Arabia

The goal of this study is to evaluate five global high-resolution satellite precipitation products (PERSIANN, PERISANN-CDR, TRMM-RT, TRMM-3B42, and CMORPH) in Saudi Arabia where only 29 rain gauges distributed in various parts of the country record daily rainfall. The satellite data are evaluated on a daily and monthly scale and at a 0.25° x 0.25° spatial resolution from January 2003 to December 2011. The satellite products are further assessed in the western and eastern parts of the country where most of the rain falls during the wet season (November through April). Evaluation of the satellite products at the western and eastern gauges shows that most of the products perform better in estimating rainfall during the wet season but perform poorly at the eastern gauges during the dry season (June to September). PERSIANN-CDR improves rainfall estimates at some locations while PERSIANN performs better at others. TRMM-3B42 exhibits better performance than TRMM-RT at all sites. Overall, in terms of most of the statistical metrics, CMORPH, PERSIANN-CDR and TRMM-3B42 performed better over Saudi Arabia. These results suggest that the satellites using both TIR and PM data for rainfall estimates do not essentially improve rainfall measurements over the satellite using PM data alone.