Intercomparison of general purpose clear sky atmospheric radiative transfer models for the millimeter/submillimeter spectral range

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Read Full Article (file size: 1391008 bytes) Cited by RADIO SCIENCE, VOL. 40, RS1007, doi:10.1029/2004RS003110, 2005 Intercomparison of general purpose clear sky atmospheric radiative transfer models for the millimeter/submillimeter spectral range C. Melsheimer Institute of Environmental Physics, University of Bremen, Bremen, Germany C. Verdes Institute of Environmental Physics, University of Bremen, Bremen, Germany S. A. Buehler Institute of Environmental Physics, University of Bremen, Bremen, Germany C. Emde Institute of Environmental Physics, University of Bremen, Bremen, Germany P. Eriksson Department of Radio and Space Science, Chalmers University of Technology, Göteborg, Sweden D. G. Feist Institute of Applied Physics, University of Bern, Bern, Switzerland S. Ichizawa Earth Observation Research and Application Center (EORC), Japan Aerospace Exploration Agency (JAXA), Tokyo, Japan V. O. John Institute of Environmental Physics, University of Bremen, Bremen, Germany Y. Kasai National Institute of Information and Communications Technology (NICT), Tokyo, Japan G. Kopp Institute of Meteorology and Climate Research, Forschungszentrum Karlsruhe GmbH, Karlsruhe, Germany N. Koulev Institute of Environmental Physics, University of Bremen, Bremen, Germany T. Kuhn Institute of Environmental Physics, University of Bremen, Bremen, Germany O. Lemke Institute of Environmental Physics, University of Bremen, Bremen, Germany S. Ochiai National Institute of Information and Communications Technology (NICT), Tokyo, Japan F. Schreier German Aerospace Center (DLR), Remote Sensing Technology Institute, Oberpfaffenhofen, Germany T. R. Sreerekha Institute of Environmental Physics, University of Bremen, Bremen, Germany M. Suzuki Earth Observation Research and Application Center (EORC), Japan Aerospace Exploration Agency (JAXA), Tokyo, Japan C. Takahashi Fujitsu FIP Corporation, Environmental System Business Division, Tokyo, Japan S. Tsujimaru Earth Observation Research and Application Center (EORC), Japan Aerospace Exploration Agency (JAXA), Tokyo, Japan J. Urban Observatoire de Bordeaux, Floirac, France Abstract We compare a number of radiative transfer models for atmospheric sounding in the millimeter and submillimeter wavelength range, check their consistency, and investigate their deviations from each other. This intercomparison deals with three different aspects of radiative transfer models: (1) the inherent physics of gaseous absorption lines and how they are modeled, (2) the calculation of absorption coefficients, and (3) the full calculation of radiative transfer for different geometries, i.e., up-looking, down-looking, and limb-looking. The correctness and consistency of the implementations are tested by comparing calculations with predefined input such as spectroscopic data, line shape, continuum absorption model, and frequency grid. The absorption coefficients and brightness temperatures calculated by the different models are generally within about 1% of each other. Furthermore, the variability or uncertainty of the model results is estimated if (except for the atmospheric scenario) the input such as spectroscopic data, line shape, and continuum absorption model could be chosen freely. Here the models deviate from each other by about 10% around the center of major absorption lines. The main cause of such discrepancies is the variability of reported spectroscopic data for line absorption and of the continuum absorption model. Further possible causes of discrepancies are different frequency and pressure grids and differences in the corresponding interpolation routines, as well as differences in the line shape functions used, namely a prefactor of (ν/ν₀) or (ν/ν₀)² of the Van-Vleck-Weisskopf line shape function. Whether or not the discrepancies affect retrieval results remains to be investigated for each application individually. Received 16 June 2004; accepted 16 November 2004; published 15 February 2005. Keywords: radiative transfer model; microwave; intercomparison. Index Terms: 0340 Atmospheric Composition and Structure: Middle atmosphere: composition and chemistry; 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0394 Atmospheric Composition and Structure: Instruments and techniques; 3360 Atmospheric Processes: Remote sensing. Read Full Article (file size: 1391008 bytes) Cited by Citation: Melsheimer, C., et al. (2005), Intercomparison of general purpose clear sky atmospheric radiative transfer models for the millimeter/submillimeter spectral range, Radio Sci., 40, RS1007, doi:10.1029/2004RS003110. Copyright 2005 by the American Geophysical Union.

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