TRMM Science Highlights and 3-hr Quasi-global Precipitation Estimates

The Tropical Rainfall Measuring Mission (TRMM) has completed more than four years in orbit. A summary of research highlights will be presented focusing on application of TRMM data to topics ranging over climate analysis, improving forecasts, precipitation processes and non-precipitation applications. One focus of the talk will be the quasi-global TRMM real-time merged rainfall analysis with 3-hr resolution, which uses TRMM to calibrate estimates from other polar-orbit and geosynchronous satellites. These rainfall estimates provide useful information for applications for assimilation into numerical models and for hydrological studies. The status of precipitation estimates from different TRMM instruments and algorithms will be described. Monthly surface rainfall estimates over the ocean based on different instruments on TRMM currently differ by 20% in overall mean. In addition, time changes in global ocean rainfall between El Nino and La Nina conditions show differences between the active and passive microwave products. Improved versions of algorithms will shortly resolve most of these differences. The TRMM rainfall estimates are intercompared among themselves and with other estimates, including those of the standard, monthly Global Precipitation Climatology Project (GPCP) analysis. A four-year TRMM rainfall climatology is presented, including anomaly fields related to the changing ENSO situation during the mission. The evolution of precipitation analysis incorporating Advanced Microwave Scanning Radiometer (AMSR) data on AQUA and ADEOS II and eventually data from the Global Precipitation Mission (GPM) will also be described.