GPROF V05B Release Notes
GPROF V05 is the rainfall algorithm used in TRMM V8. It matches in all ways the algorithm from the retrieval for GPM GMI and other satellites in the constellation. The Goddard Profiling Algorithm is a Bayesian approach that nominally uses the GPM Combined algorithm to create it's a-priori databases. Given the importance of these databases to the final product, they are worth reviewing before discussing particular changes to the algorithm. GPROF V03 was implemented at the launch of the GPM mission and thus had no databases from the GPM satellite itself. Instead, databases were made from a combination of TRMM, Cloudsat, ground based radars and models. V04 used the GPM generated databases but had a very short lead time as the radar and combined algorithm were in flux until nearly the date of the public release. Because the V04 of the Combined algorithm appeared to significantly overestimate precipitation over land, the a-priori databases were constructed from the Combined Algorithm (V04) over ocean, but the DPR Ku (V04) over land and coastal regions. The very short lead time to produce the a-priori databases led to insufficient testing of GPROFV04 that resulted in some less-than ideal retrievals.