TRMM 2A12 Land Precipitation Product : Status and Future Plans(3. TRMM Microwave Imager (TMI),<Special Issue>Precipitation Measurements from Space)

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概要

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• The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) 2A12 product consists of unique components configured for land and oceanic precipitation retrievals. This design was based on the vastly different physical characteristics of the retrieval, involving primarily emission over ocean and entirely scattering over land. This paper describes the current status of the TRMM Version 6 (V6) 2A12 product over land and envisioned improvements for TRMM TMI V7 and GPM GMI V1. On a global scale, the 2A12 land algorithm exhibits biases when compared with the TRMM 2A25 (Precipitation Radar (PR) based) and rain gauges. These range from 6 percent for GPCC to 20 percent for 2A25. Closer comparison also reveals regional and seasonal biases, with the largest positive biases found in warm-season convective zones and over semi-arid regions. Some negative biases are found in warm-rain precipitation regimes where scattering at 85GHz is unable to detect a precipitation signal. On an instantaneous time scale, 2A12 land also produces a positive bias when compared with high-quality radar data from Melbourne, Florida, a TRMM ground validation site. The largest discrepancies occur for rain rates of less than 2mm h^<-1>. A number of known "anomalies" are highlighted, including overestimation of rainfall in deep convective systems, underestimation in warm-rain regimes, and a number of features associated with the screening component of the algorithm (e.g., snow cover, deserts, etc.). Future improvements for TRMM TMI V7 are described and include the use of ancillary data to determine the underlying surface characteristics and the development of improved brightness-temperature to rain-rate relationships with a more robust data set of TMI and PR matchups, stratified by atmospheric parameters (i.e., surface temperature, atmospheric moisture, etc.) obtained from Numerical Weather Prediction (NWP) model fields. Finally, the promise of an improved land algorithm through the use of high-frequency microwave measurements is described. This will form the basis for the Global Precipitation Measurement (GPM) Global Microwave Imager (GMI) V1 algorithm.

• 2009-03-31

著者

• Wolff Dave

  Nasa Gsfc

• Wang Nai-yu

  Earth System Science Interdisciplinary Center (essic) University Of Maryland

• LIU Chuntao

  Department of Meteorology, University of Utah

• FERRARO Ralph

  NOAA NESDIS

• ZIPSER Ed

  Department of Meteorology, University of Utah

• KUMMEROW Chris

  Department of Atmospheric Sciences, Colorado State University

• Kummerow Chris

  Department Of Atmospheric Sciences Colorado State University

• Zipser Ed

  Department Of Meteorology University Of Utah

• Liu Chuntao

  Department Of Meteorology University Of Utah

関連論文

• TRMM 2A12 Land Precipitation Product : Status and Future Plans(3. TRMM Microwave Imager (TMI),Precipitation Measurements from Space)

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