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| Titel |
A fast method to compute Three-Dimensional Infrared Radiative Transfer in non scattering medium |
| VerfasserIn |
Laurent Makke, Luc Musson-Genon, Bertrand Carissimo |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091024
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| Publikation (Nr.) |
 EGU/EGU2014-5289.pdf |
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| Zusammenfassung |
| The Atmospheric Radiation field has seen the development of more accurate and faster
methods to take into account absoprtion in participating media. Radiative fog appears with
clear sky condition due to a significant cooling during the night, so scattering is
left out. Fog formation modelling requires accurate enough method to compute
cooling rates. Thanks to High Performance Computing, multi-spectral approach of
Radiative Transfer Equation resolution is most often used. Nevertheless, the coupling
of three-dimensionnal radiative transfer with fluid dynamics is very detrimental
to the computational cost. To reduce the time spent in radiation calculations, the
following method uses analytical absorption functions fitted by Sasamori (1968) on
Yamamoto’s charts (Yamamoto,1956) to compute a local linear absorption coefficient. By
averaging radiative properties, this method eliminates the spectral integration. For an
isothermal atmosphere, analytical calculations lead to an explicit formula between
emissivities functions and linear absorption coefficient. In the case of cooling to space
approximation, this analytical expression gives very accurate results compared
to correlated k-distribution. For non homogeneous paths, we propose a two steps
algorithm. One-dimensional radiative quantities and linear absorption coefficient
are computed by a two-flux method. Then, three-dimensional RTE under the grey
medium assumption is solved with the DOM. Comparisons with measurements of
radiative quantities during ParisFOG field (2006) shows the cability of this method to
handle strong vertical variations of pressure/temperature and gases concentrations. |
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