ESTIMATION OF LAND-SURFACE EMISSIVITY DIFFERENCES IN THE SPLIT-WINDOW CHANNELS OF AVHRR

A method for estimating the difference between the channel emissivities in NOAA-AVHRR Channels 4 and 5 is proposed and applied to a data set from the HAPEX-MOBILHY experiment. The method is based on the separation between the atmospheric and emissivity effects in the brightness temperature difference measured with AVHRR Channels 4 and 5. Atmospheric profiles coincident to the satellite overpass and a radiative transfer model are required to estimate the atmospheric correction for brightness temperatures. With this procedure, the emissivity difference DELTAepsilon is obtained at the satellite spatial and spectral resolution, which has a great interest for correcting thermal images with the split-window technique. The order of magnitude of the error related to the method proposed has been estimated by means of a sensitivity analysis to be better than 0.005.