For the past year (by conference time) the authors have run a real-time processing system that combines IR and microwave data into 0.25°x0.25° gridded precipitation estimates over the latitude band +/-50°. One unique feature of this system is that all input passive microwave precipitation estimates are calibrated to a single instrument. Presently, SSM/I, AMSU, and AMSR estimates are calibrated to the TRMM Microwave Imager (TMI) precipitation estimates, and then merged together in 3-hourly fields. These merged microwave estimates are then used to create a calibrated IR estimate in a Probability-Matched-Threshold approach for each hour. The merged microwave and IR estimates are combined for each 3-hourly interval. A closely related post-real-time system has been developed and implemented for Version 6 of the operational TRMM Science Data and Information System that features several improvements, including incorporation of monthly gauges and data-set processing back to January 1998.

One facet of the talk will focus on innovative applications that take advantage of the fine temporal and spatial resolution. These include monitoring excessive precipitation events, depicting storm accumulations, and producing up-to-date, quantitative displays of precipitation associated with ENSO. A second facet of the talk will be a discussion of the relationship between and comparative validations of the real-time and post-real-time precipitation and error estimate products. Finally, the talk will end with a summary of our state of knowledge of how to build such algorithms and the outstanding science questions in this area. As just one example, 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. However, extensive analysis must be done to determine the optimum method to synthesize these data into a finely resolved grid in space and time.