Dust Detection and Aerosol Properties Over Arabian Sea Using MODIS Data

The present study deals with the use of Moderate Resolution Imaging Spectroradiometer (MODIS) thermal infrared bands in the dust detection. Eight dust storm cases over the Arabian Sea have been selected (four TERRA and four AQUA) during the year 2002-2008. The brightness temperature (BT) difference method has been applied on MODIS thermal bands 29 (8 mu m), 31 (11 mu m) and 32 (12 mu m) to detect dust storms over the Arabian Sea. The performance assessment of BT differences (BT29-BT31 and BT31-BT32) has shown that BT31-BT32 has performed better to BT29-BT31. We suggest that BT31-BT32 is an effective combination of MODIS bands for dust detection over oceans and sea. The maximum (Dmax) and minimum dust (Dmin) intensity locations have also been identified in all the eight dust storm cases. The aerosol properties (aerosol optical thickness, tau; asymmetry factor g and Angstrom exponent alpha) over Dmax and Dmin have been studied using MODIS Level 2 data. In AQUA dust storms cases tau values (Dmax) were higher than TERRA dust cases, whereas g values were nearly same. The alpha was always positive in case of TERRA dust cases; however in AQUA negative alpha was also reported. Afternoon dust storms are more intense compared to forenoon dust storms and dust particles are also coarser.