26th Conference on Hurricanes and Tropical Meteorology

Wednesday, 5 May 2004
Consistency check of drop size distribution in rain retrievals with a combination of TRMM Microwave Imager and Precipitation Radar observations
Richelieu Room (Deauville Beach Resort)
Shoichi Shige, Japan Exploration Agency, Tokyo, Japan; and S. Shimizu, N. Takahashi, T. Iguchi, T. Kozu, and K. Okamoto
Poster PDF (137.3 kB)
The TRMM Microwave Imager (TMI) and Precipitation Radar (PR) have been providing distribution of rainfall throughout the Tropics and contributed significantly towards reducing uncertainty in satellite estimates of rainfall. Although differences in global averaged rainfall between the two sensors have been reducing, regional and seasonal differences still exist. Possible error sources are static model assumptions involved with individual retrieval algorithm. For example, the PR algorithm (2A25: Iguchi et al. 2000) uses a globally averaged drop size distribution (DSD) model, which strongly affects PR retrievals because information on the DSD enters radar echoes through the six moment of the DSD. In this study, the consistency between TMI and PR sensors is investigated focusing on the DSD model, similar to Viltard et al. (2000) but with increased numbers of cases. We obtain simulated brightness temperature from PR precipitation profiles at the same frequencies as those of the TMI, with a forward radiative transfer model (Liu 1998). Comparison of the observed and simulated brightness temperature especially, in low-frequency channels, is conducted, because TMI brightness temperatures in low-frequency channels are insensitive to DSD. We examine whether or not the DSD model assumed by the PR algorithm produces good or poor agreement between the observed and simulated brightness temperature.

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