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An Intercomparison of Radiation Codes for Retrieving Upper Tropospheric Humidity in the 6.3-micron Band: A Report from the 1st GVaP WorkshopAn intercomparison of radiation codes used in retrieving upper tropospheric humidity (UTH) from observations in the v2 (6.3 microns) water vapor absorption band was performed. This intercomparison is one part of a coordinated effort within the GEWEX Water Vapor Project (GVaP) to assess our ability to monitor the distribution and variations of upper tropospheric moisture from space-borne sensors. A total of 23 different codes, ranging from detailed line-by-line (LBL) models, to coarser resolution narrow-band (NB) models, to highly-parameterized single-band (SB) models participated in the study. Forward calculations were performed using a carefully selected set of temperature and moisture profiles chosen to be representative of a wide range of atmospheric conditions. The LBL model calculations exhibited the greatest consistency with each other, typically agreeing to within 0.5 K in terms of the equivalent blackbody brightness temperature (T(sub b)). The majority of NB and SB models agreed to within +/- 1 K of the LBL models, although a few older models exhibited systematic T(sub b) biases in excess of 2 K. A discussion of the discrepancies between various models, their association with differences in model physics (e.g. continuum absorption), and their implications for UTH retrieval and radiance assimilation is presented.
Document ID
19990116116
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Soden, B.
(National Oceanic and Atmospheric Administration Princeton, NJ United States)
Tjemkes, S.
(European Organization for the Exploitation of Meteorological Satellites Darmstadt, Germany)
Schmetz, J.
(European Organization for the Exploitation of Meteorological Satellites Darmstadt, Germany)
Saunders, R.
(European Centre for Medium-Range Weather Forecasts Reading, United Kingdom)
Bates, J.
(National Oceanic and Atmospheric Administration Boulder, CO United States)
Ellingson, B.
(Maryland Univ. College Park, MD United States)
Engelen, R.
(Colorado State Univ. Fort Collins, CO United States)
Garand, L.
(Atmospheric Environment Service Canada)
Jackson, D.
(National Oceanic and Atmospheric Administration Boulder, CO United States)
Jedlovec, G.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Meteorology And Climatology
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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