A first comparison of global merged precipitation analyses with Tropical Rainfall Measuring Mission (TRMM) data

The Tropical Rainfall Measuring Mission (TRMM) spacecraft was launched in November 1997 to study the tropical rainfall for a nominal period of three years. Three instruments onboard the TRMM spacecraft are used to produce independent/combined rainfall estimates-the Precipitation Radar (PR), the TRMM Microwave Imager (TMI), and the Visible and Infrared Scanner (VIRS). This study depends on precipitation estimates from all three instruments. The goal of this analysis is to evaluate the relative quality of tropical precipitation estimates produced using data from TRMM in combination with precipitation estimates from other, independent sources. The quality of these “TRMM and other sources” precipitation estimates is assessed through comparison with selected western tropical Pacific atoll rain gauge data. To aid in the assessment, global merged precipitation data from the Global Precipitation Climatology Project (GPCP) is compared with both the “TRMM and other sources” data and the western tropical Pacific atolls. The “ITRMM and other sources” estimate uses the same combination technique as that used in the GPCP estimate, so the comparison between the two will primarily reflect differences in the input data quality