Satellite aerosol optical thickness retrieval over land with contrast reduction analysis using a variable window size

A new method for retrieving aerosol optical thickness (AOT) over land is presented. The method that is based on the contrast reduction analysis uses a variable window size in the calculations of the so-called structure function. The window size is automatically selected on a pixel-by-pixel basis through the use of a simple ´homogeneity´ criterion. The proposed method that needs no a-priori information has been applied to both Landsat-TM and NOAA-AVHRR data. The retrieved AOT values show higher correlations in in situ chemical measurements compared to the classical approach that adopts a constant window size for the target areas.