"Pixel-scale composite top-of-the-atmosphere clear-sky reflectances for Meteosat-7 visible data"
Earth and related Environmental sciences
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A new method to estimate composite top of the atmosphere (TOA) visible clear-sky reflectances for wide narrow band geostationary satellites such as the Meteosat constellation is presented. This method relies on some a priori knowledge of angular variations of TOA broadband reflectances associated with clear-sky conditions above mean surface types through the use of the clear-sky Cloud and the Earth’s Radiant Energy System (CERES) shortwave broadband angular dependency models (ADMs). Each pixel (or Earth location) viewed from such geostationary imager at a given daytime is associated with a reflectance time series made up of its chronological daily measurements. This time series can be seen as a clear-sky visible narrow band reflectance curve of the associated pixel surface plus an additive random noise modeling cloudy conditions above it. On the basis of this assumption, TOA clear-sky broadband reflectances extracted from the CERES ADMs are used to compute curve-driven fifth percentiles on these time series in order to estimate the TOA clear-sky visible narrow band reflectance curves for all pixels, while the percentile approach exhibits onldy a reduced sensitivity to cloud shadows. Benefits of our method are discussed with respect to its application to 7 months of Meteosat-7 daytime visible narrow band measurements. Finally, the performance of our algorithm is assessed through comparisons with its predicted and associated International Cloud Climatology Project DX clear-sky values with respect to a visually generated clearsky pixels database. INDEX TERMS: 3359 Meteorology and Atmospheric Dynamics: Radiative processes; 3360 Meteorology and Atmospheric Dynamics: Remote sensing; 3394 Meteorology and Atmospheric Dynamics: Instruments and techniques; KEYWORDS: pixel-scale, TOA composite, clear-sky, Meteosat-7 imager
CitationIpe, A.; Clerbaux, N.; Bertrand, C.; Dewitte, S.; Gonzalez, L. (2003). "Pixel-scale composite top-of-the-atmosphere clear-sky reflectances for Meteosat-7 visible data". , Issue Journal of Geophysical Research, 108(D19), 4612,, IRM, DOI: doi:10.1029/2002JD002771.