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Calibration Plans for the Global Precipitation Measurement (GPM)The Global Precipitation Measurement (GPM) is an international effort led by the National Aeronautics and Space Administration (NASA) of the U.S.A. and the National Space Development Agency of Japan (NASDA) for the purpose of improving research into the global water and energy cycle. GPM will improve climate, weather, and hydrological forecasts through more frequent and more accurate measurement of precipitation world-wide. Comprised of U.S. domestic and international partners, GPM will incorporate and assimilate data streams from many spacecraft with varied orbital characteristics and instrument capabilities. Two of the satellites will be provided directly by GPM, the core satellite and a constellation member. The core satellite, at the heart of GPM, is scheduled for launch in November 2007. The core will carry a conical scanning microwave radiometer, the GPM Microwave Imager (GMI), and a two-frequency cross-track-scanning radar, the Dual-frequency Precipitation Radar (DPR). The passive microwave channels and the two radar frequencies of the core are carefully chosen for investigating the varying character of precipitation over ocean and land, and from the tropics to the high-latitudes. The DPR will enable microphysical characterization and three-dimensional profiling of precipitation. The GPM-provided constellation spacecraft will carry a GMI radiometer identical to that on the core spacecraft. This paper presents calibration plans for the GPM, including on-board instrument calibration, external calibration methods, and the role of ground validation. Particular emphasis is on plans for inter-satellite calibration of the GPM constellation. With its Unique instrument capabilities, the core spacecraft will serve as a calibration transfer standard to the GPM constellation. In particular the Dual-frequency Precipitation Radar aboard the core will check the accuracy of retrievals from the GMI radiometer and will enable improvement of the radiometer retrievals. Observational intersections of the core with the constellation spacecraft are essential in applying this technique to the member satellites. Information from core spacecraft retrievals during intersection events will be transferred to the constellation radiometer instruments in the form of improved calibration and, with experience, improved radiometric algorithms. In preparation for the transfer standard technique, comparisons using the Tropical Rainfall Measuring Mission (TRMM) with sun-synchronous radiometers have been conducted. Ongoing research involves study of critical variables in the inter-comparison, such as correlation with spatial-temporal separation of intersection events, frequency of intersection events, variable azimuth look angles, and variable resolution cells for the various sensors.
Document ID
20030032207
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Bidwell, S. W.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Flaming, G. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Adams, W. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Everett, D. F.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mendelsohn, C. R.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Smith, E. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Turk, J.
(Naval Research Lab. Monterey, CA, United States)
Date Acquired
August 21, 2013
Publication Date
August 1, 2002
Subject Category
Earth Resources And Remote Sensing
Meeting Information
Meeting: 2nd International Microwave Radiometer Calibration Workshop
Location: Barcelona
Country: Spain
Start Date: October 9, 2002
End Date: October 11, 2002
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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