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A Method to Retrieve Rainfall Rate over Land from TRMM ObservationsTropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) observations over mesoscale convective systems (MCSs) reveal that there are localized maxima in the rain rate with a scale of about 10 to 20 km that represent thunderstorms (Cbs). Some of these Cbs are developing or intense, while others are decaying or weak. These Cbs constitute only about 20 % of the rain area of a given MCS. Outside of Cbs, the average rain rate is much weaker than that within Cbs. From an analysis of the PR data, we find that the spatial distribution of rain and its character, convective or stratiform, is highly inhomogeneous. This complex nature of rain exists on a scale comparable to that of a Cb. The 85 GHz brightness temperature, T85, observations of the TRMM Microwave Imager (TMI) radiometer taken over an MCS reflect closely the PR rain rate pattern over land. Local maxima in rain rate shown by PR are observed as local minima in T85. Where there are no minima in T85, PR observations indicate there is light rain. However, the TMI brightness temperature measurements (Tbs) have poor ability to discriminate convective rain from stratiform rain. For this reason, a TMI rain retrieval procedure that depends primarily on the magnitude of Tbs performs poorly. In order to retrieve rain rate from TMI data on land one has to include the spatial distribution information deduced from the T85 data in the retrieval method. Then, quantitative estimation of rain rate can be accomplished. A TMI rain retrieval method developed along these lines can yield estimates of rain rate and its frequency distribution which agree closely with that given by PR. We find the current TRMM project TMI (Version 5) rain retrieval algorithm on land could be improved with the retrieval scheme developed here. To support the conceptual frame work of the rain retrieval method developed here, a theoretical analysis of the TMI brightness temperatures in convective and stratiform regions is presented.
Document ID
20030020917
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Prabhakara, C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Iacovazzi, R., Jr.
(Science Systems and Applications, Inc. Lanham, MD, United States)
Yoo, J.-M.
(Ewha Woman's Univ. Seoul, Korea, Republic of)
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Subject Category
Meteorology And Climatology
Meeting Information
Meeting: International Tropical Rainfall Measuring Mission(TRMM)Science Meeting
Location: Honolulu, HI
Country: United States
Start Date: July 22, 2002
End Date: July 26, 2002
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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