An Intercalibration of METEOSAT-1 and GOES-2 Visible and Infrared Measurements

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  • 1 Atmospheric Sciences Division, NASA Langley Research Center, Hampton, VA 23665
  • 2 Atmospheric Physics Group, Imperial College, London SW7 2BZ, UK
  • 3 Atmospheric Sciences Division, NASA Langley Research Center, Hampton, VA 23665
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Abstract

An intercomparison between radiative parameters determined from visible and infrared channels of the METEOSAT-1 and GOES-2 geosynchronous satellites has been carried out using data obtained over the central Atlantic Ocean for 5 November 1978. Hourly visible-infrared measurement pairs at a nominal resolution of 5 km (METEOSAT) or 8 km (GOES) have been stored in 1° × 1° longitude-latitude regions. For the infrared intercomparisons, the GOES 11.5 μm radiance has been compared to METEOSAT infrared counts. The scatter in partly cloudy regions is interpreted as being caused by meteorological differences arising from differences in measurement time between the two data sets. For the visible intercomparison, the GOES measurements for clear and cloudy scenes have first been converted with the aid of scene-dependent angular reflectance and albedo models to estimates of the filtered shortwave radiance that GOES would have measured had it been in the METEOSAT position. This value has then been compared to METEOSAT counts for the shortwave channel. The results indicate that earlier METEOSAT calibrations made from airplane overflights of a limited variety of surfaces are applicable to much larger areas of cloud and ocean.

Abstract

An intercomparison between radiative parameters determined from visible and infrared channels of the METEOSAT-1 and GOES-2 geosynchronous satellites has been carried out using data obtained over the central Atlantic Ocean for 5 November 1978. Hourly visible-infrared measurement pairs at a nominal resolution of 5 km (METEOSAT) or 8 km (GOES) have been stored in 1° × 1° longitude-latitude regions. For the infrared intercomparisons, the GOES 11.5 μm radiance has been compared to METEOSAT infrared counts. The scatter in partly cloudy regions is interpreted as being caused by meteorological differences arising from differences in measurement time between the two data sets. For the visible intercomparison, the GOES measurements for clear and cloudy scenes have first been converted with the aid of scene-dependent angular reflectance and albedo models to estimates of the filtered shortwave radiance that GOES would have measured had it been in the METEOSAT position. This value has then been compared to METEOSAT counts for the shortwave channel. The results indicate that earlier METEOSAT calibrations made from airplane overflights of a limited variety of surfaces are applicable to much larger areas of cloud and ocean.

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