Aerosol optical depth retrieval over land using MODIS data and its application in detection of dust event

Aerosol optical depth (AOD) is a significant indicator of dust episode. However, AOD retrieval over land still remains a difficult task because the measured signal is a composite of reflectance of sunlight by the variable surface covers and back scattering by the semitransparent aerosol layer. In this paper, an approach using bi-angle with Moderate Resolution Imaging Spectroradiometer (MODIS) data was presented. The derived AOD is compared to AERONET observations in the Washington State area and a retrieval error within 18% is found. Moreover, a dust episode in Washington State on October 4, 2009 was presented; we have analyzed the advection and dispersion of this event to get the possible source areas for the episode and its influence in the next day under the meteorological conditions.