A new processing system has been developed to combine IR and microwave data into 0.25°x0.25° gridded precipitation estimates in near-real time over the latitude band +/-50°. Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) precipitation estimates are used to calibrate SSM/I estimates, and AMSR estimates, when available. The merged microwave estimates are then used to create a calibrated IR estimate in a Probability-Matched-Threshold approach for each individual hour. The microwave and IR estimates are combined for each 3-hour interval. Early results will be shown, including typical tropical and extratropical storm evolution and examples of the diurnal cycle. Major issues will be discussed, including the choice of IR algorithm, the approach for merging the IR and microwave estimates, extension to higher latitudes, retrospective processing back to 1999, and extension to the GPCP One-Degree Daily product (for which the authors are responsible).

The work described here provides one approach to using data from the future NASA Global Precipitation Measurement program, which is designed to provide full global coverage by low-orbit passive microwave satellites every three hours beginning around 2008.