Initial Gprof Results Using a GPM Derived Database

Abstract:

The GPM Microwave Imager (GMI) algorithm used for at-launch products was constructed from a combination of sources. Over ocean, it used the physical a-priori database that was originally constructed for TRMM using TRMM PR and TMI to constrain the solution. The physical nature of this database allowed for the expansion to GMI channels although the high frequency channels were not actually constrained (n > 85 GHz) in the physical solution. The database was modified by removing the lowest atmospheric layers for regions with SST and TPW outside the realm of TRMM observations. Over land, the GPM at-launch database was constructed using coincident overpasses of individual radiometers with coincident data from the National Severe Storms Laboratory’s National Mosaic and multi-sensor Quantitative precipitation estimation (NMQ) system. For the retrieval, GMI was assumed to follow the SSMIS channels. With more than 9 months of GMI data collected, this talk will focus on the quantitative improvements that were achieved by using an a-priori database consistent with the channels and resolution of GMI instead of relying on SSMIS channels. The talk will also describe the technique being employed to develop a more physical database that will be implemented approximately 6 months after the one-year anniversary of GPM.