NOAA Climate Data Record (CDR) of Visible and Near Infrared Reflectance from AVHRR, Version 1.0

The AVHRR visible gains and offsets convert GAC pixel level counts to radiances and are provided for each visible band encompassing TIROS-N, NOAA-6 through NOAA-19 and Metop-A and B satellites. The resulting radiances are referenced to the Aqua-MODIS band 1 and 2 absolute calibration. Instructions are also given to convert AVHRR-3 (NOAA-15 to Metop-B) GAC high and low gain counts to the proper radiance. The gains vary temporally and are given as a function of day since launch, where the launch date is provided. The satellite and band specific solar constants are also provided to convert radiances into reflectances based on the solar incoming irradiance used by the MODIS Science Team. The resulting radiance uncertainty is given in %. The calibration coefficients are only valid for the start and end dates listed for each satellite. Three data variables are derived from 4 km AVHRR Global Area Coverage data: Calibrated 0.63 micron channel reflectance (unitless), Calibrated 0.86 micron reflectance (unitless), Calibrated 1.61 micron reflectance (unitless)