Retrieval of Aerosol from CBERS02B using Contrast Reduction Method in Beijing

Tropospheric aerosols play an important role in the Earth radiation budget directly through scattering and absorption of solar and infrared radiation, and indirectly by modifying cloud microphysical and radiative properties. Satellite remote sensing provides a means to derive aerosol distribution at global scales. The common operational algorithm to retrieve aerosol optical depth (AOD) is dark pixels method based on the atmospheric effect on the path radiance. However, when the land surface has a high reflectance, this method always becomes invalid. Another way was contrast reduction method (or structure function method) using the change in contrast for several scenes to determine the optical thickness between the scenes. China Brazil Earth Resources Satellite (CBERS) series carry high resolution CCD camera with a small scan degree, which is fit to retrieve AOD using contrast reduction method. CBERS02B was launched on 19^th September, 2007, and the CCD camera has been calibrated on board. This paper retrieves AOD from CBERS02B using contrast reduction method in Beijing urban area. The experiment result overestimates the AOD by about 0.2 while has the right tend.