ESTIMATION OF LAND-SURFACE EMISSIVITY DIFFERENCES IN THE SPLIT-WINDOWCHANNELS OF AVHRR

A method for estimating the difference between the channel emissivitie s 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 separat ion between the atmospheric and emissivity effects in the brightness t emperature difference measured with AVHRR Channels 4 and 5. Atmospheri c profiles coincident to the satellite overpass and a radiative transf er model are required to estimate the atmospheric correction for brigh tness temperatures. With this procedure, the emissivity difference DEL TAepsilon is obtained at the satellite spatial and spectral resolution , which has a great interest for correcting thermal images with the sp lit-window technique. The order of magnitude of the error related to t he method proposed has been estimated by means of a sensitivity analys is to be better than 0.005.