JP Journal of Heat and Mass Transfer
Volume 3, Issue 2, Pages 73 - 93
(June 2009)
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SPATIAL AND TEMPORAL DISTRIBUTIONS OF DOWNWELLING SOLAR RADIATION IN CAMEROON AS DERIVED USING A PARAMETERIZED SOLAR RADIATIVE TRANSFER MODEL IN A MOLECULAR ATMOSPHERE
L. Akana Nguimdo (Cameroon) and D. Njomo (Cameroon)
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Abstract: This study presents surface and atmospheric solar radiation fluxes results obtained in Cameroon using a combination of geographical considerations and the parameterized radiative transfer model called CLIRAD-SW. This model is a plane parallel radiative transfer model developed by Minh-Dah Chou and J. Max Suarez from the NASA GSFC in 1999. It derives surface solar radiation, upward and downward fluxes within the atmosphere along with local heating rate from calculated atmospheric transmissivities and reflectivities using the two stream adding method. Following Klein, new average solar days are proposed. To assess the performances of this method, we compared the model results with the January and February (zero Octa nebulosity) ground-based measured global radiation data obtained using Eppley PSP Pyranometers for the Banyo, Poli and Garoua stations. Strong correlations (99%) were observed suggesting that the method is appropriate for retrieving solar irradiation even in case of a turbid atmosphere. Following this overall agreement, a one year hourly surface and TOA solar fluxes are presented for the Yaound� station. Similar monthly averaged fluxes were also presented for the ten meteorological stations across the country. The model has also been used to infer the upward and downward diffuse and direct fluxes within the molecular atmosphere of Yaound� and Garoua which are representative of the whole Cameroon solar climate. |
Keywords and phrases: molecular atmosphere, CLIRAD-SW, plane parallel atmosphere, radiative transfer model, two stream adding method, TOA, SW-fluxes, average solar days. |
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