Primary Validation of the Syntem Aerosol Retrieval Model over Beijing Area Using Aeronet Data

Atmospheric aerosol, as particulate matter suspended in the air, exists in a variety of forms such as dust, fume and mist. It deeply affects climate and land surface environment in both regional and global scales, and furthermore, lead to be hugely much influence on human health. For the sake of effectively monitoring it, satellite remote sensing data are used to inverse aerosol optical depth and become the one of the most available and effective approach. With the launches of sensors several aerosol retrieval models were developed. By exploiting the synergy of MODIS data from two successive orbit of lesser interval for the same area, nonlinear equations can be solved by means of numerical methods to retrieve simultaneously the ground surface reflectance, Angstrom exponent, and aerosol optical thickness of two overpasses. The model showed promising potential to address the aerosol retrieval over higher reflective surface over land, and need to be validated and analysed. In this paper, a regional validation package for satellite aerosol optical thickness retrieval using the Aerosol Robotic Network (AERONET) observations as ground truth is described. To standardize the validation procedure, the optimum time-space match-up window, the ensemble statistical analysis method, the best selection of AERONET channels, and the numerical scheme used to interpolate/extrapolate these observations to satellite channels have been identified through sensitivity studies. More than 30 groups of MODIS data, during December 1st to 31st of 2007, were used to validate the model. All of this data are about Beijing and area around Beijing. The MODIS/AERONET τ regression has an equation of: y = 1.0937x 0.0373.