Identification of dust transport patterns and sources by using MODIS: a technique developed to discriminate dust and clouds

Abstract

This study focuses on exploring the meteorological factors behind dust emergence and spread over Baluchistan in the post-monsoon season, as much of the existing research has been done on spring episodes. With the integration of remote sensing and meteorological methods, efforts were made to explore the relationship of dust storms with land-atmospheric conditions like surface temperature and aerosol optical depth (AOD) in the selected season. To map dust spatial distribution, a cloud-free product of brightness temperature difference (BTD) composite from MODIS terra level 1B emissive bands was prepared and classified using maximum likelihood technique. Two case studies of October 2004 and December 2011 exhibited the short-term cooling effect on the surface due to increased AOD. Dominant synoptic patterns of cold trough front formation with low-pressure centre development over eastern Iran were found as a significant feature of dust mobility towards warmer Baluchistan. Back trajectory analysis revealed that dust from south western Kazakhstan and eastern Europe converged over land of Kyrgyzstan and Tajikistan, which may have instigated its uplift over Helmand Basin. Evidence of a dominant effect of air masses from Middle East, Iran and Iraq was found in post-monsoon dust episodes.