Characterization of a Regional Dust Storm Using RAMAN Lidar Over the Western Indian Region

The present study investigates a dust storm (DS, on 5th May 2016) over a semi-arid western-Indian region, Ahmedabad using a ground-based Raman Lidar (RL), satellite datasets, and model simulations. The Moderate Resolution Imaging Spectroradiometer (MODIS) corrected reflectance images from Terra and Aqua satellites showed a heavy dust layer over the Ahmedabad region transported from the Arabian Peninsula and the Middle East. Horizontal visibility decreased sharply, falling less than 1 km on the DS day. RL is used to monitor the diurnal variation of the dust aerosol layer from the surface to about 3 km during DS. The retrieved aerosol optical depth (AOD) using the RL and MODIS shows high AOD values on the DS day (AOD similar to 2.2 and 0.85) attributed to higher dust loading in comparison to normal days. Results indicate that the ultraviolet aerosol index (UVAI) increased by twice (similar to 3) during DS day in comparison with dust-free day (UVAI similar to 1.4). The WRF-Chem model reasonably reproduced the spatial distribution of PM10 and PM2.5 concentrations, exhibiting higher concentrations during the DS when compared to ECMWF-CAMS.