Satellite-Derived Surface Radiation Budget over the African Continent. Part I Estimation of Downward Solar Irradiance and Albedo

Downward surface solar irradiance and albedo of the African continent are estimated from Meteosat B2 data at 30-km spatial resolution. The algorithm, based on Dedieu et al.’s approach, is verified against other satellite estimates and ground-based measurements. In the computations, the International...

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Bibliographic Details
Published inJournal of climate Vol. 14; no. 1; pp. 45 - 58
Main Authors Ba, Mamoudou B., Frouin, Robert, Nicholson, Sharon E., Dedieu, Gérard
Format Journal Article
LanguageEnglish
Published Boston, MA American Meteorological Society 01.01.2001
Subjects
Aerosols
Albedo
Atmospherics
Calibration
Clouds
Earth, ocean, space
Exact sciences and technology
External geophysics
Meteorology
Meteors
Optical thickness
Radiative transfer. Solar radiation
Reflectance
Signal reflection
Solar irradiance
Sahel
Africa
Libya
Climatology
Uncertainty
Clouds
Ground based measurement
Radiation balance
Satellite observation
Irradiance
Calibration
Algorithm
Meteosat satellites
Albedo
Clear sky
Vegetation
Aerosols
Solar radiation
Reflectance
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Summary:Downward surface solar irradiance and albedo of the African continent are estimated from Meteosat B2 data at 30-km spatial resolution. The algorithm, based on Dedieu et al.’s approach, is verified against other satellite estimates and ground-based measurements. In the computations, the International Satellite Cloud Climatology Project’s (ISCCP) radiometric calibration is adjusted using the Libyan desert as a reference target of constant reflectance properties. Surface albedo is corrected for sun zenith angle effects, allowing for better detection of seasonal changes due to the vegetation cycle. The estimates obtained with Meteosat B2 data agree generally well with other satellite estimates, although biases of 20 W m−2(downward surface solar irradiance) and 0.15 (surface albedo) are obtained in some cases. There is evidence, from comparisons with surface measurements, that the clear-sky downward surface solar irradiance is overestimated over semiarid regions of Africa because of uncertainties in aerosol characteristics. In the Sahel region, where spatial albedo gradients are high, it is advantageous to use 30-km Meteosat B2 products instead of the current, coarser 280-km-resolution ISCCP products.
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ISSN:0894-8755
1520-0442
DOI:10.1175/1520-0442(2001)014<0045:SDSRBO>2.0.CO;2