Extending the Precipitation Map Offshore Using Daily and 3-Hourly Combined Precipitation Estimates

One of the frustrations in studying landfalling extratropical cyclones along the Pacific Coast is the lack of antecedent data over the ocean, particularly precipitation. Recent research on combining various satellite-based precipitation estimates opens the possibility of realistic, even quantitative precipitation estimates on a 1x1-deg grid as daily accumulations, with 3-hourly instantaneous estimates presently in development. This paper describes these new datasets. For both datasets, 3-hourly geosynchronous infrared (geo-IR) data are thresholded and scaled with higher quality data to form the bulk of estimates in the band 40N-S. Outside of that band, the estimate is based on revised estimates from Television Infrared Operational Satellite (TIROS) Operational Vertical Sounder (TOVS). Unlike the daily estimates, the 3-hourly estimates explicitly merge the relatively high-quality passive microwave estimates with the geo-IR- and TOVS-based estimates. Preliminary validation is presented, and we discuss the data boundary at 40N (and 40S), which is much more homogeneous than we anticipated. Current developments, data availability, and prospects for the future, including the Global Precipitation Mission, will be discussed.