2001 Volume 21 Issue 3 Pages 260-271
An algorithm is presented for the atmospheric correction of satellite data in the visible and near-infrared spectral region. The algorithm consists of analytic equations which are described only with the radiance components easily obtained with a radiation transfer code such as MODTRAN3. A three-step approach is introduced to precisely evaluate the pixel reflectance. In the first step, the path radiance is removed and in the second and the third steps, the adjacency effect from the neighboring pixels is removed. Using this method, a sensitivity analysis is performed for the NOAA AVHRR channel 1 and channel 2. To obtain a test image, we consider the multiply scattered component and the indirectly ground-reflected component, both of which are dependent on an average reflectance around the target pixel. It is found that a precision of about 1 % (channel 1) and 0.5 % (channel 2) can be obtained with respect to the pixel reflectances if the same atmospheric conditions are applied both to the generation of the test image and to the retrieval of the reflectance image. The method is actually applied to AVHRR images with the optical thickness obtained from ground measurements synchronized with the satellite overpass. The present algorithm is suitable for cases in which the surface reflectance changes on a pixel by pixel basis. Since the algorithm is described with radiance components, its application to any type of satellite sensor is quite straightforward as compared with the conventional lookup table approach.
