Recent Regime Shifts in Mineral Dust Trends Over South Asia From Long-Term CALIPSO Observations

Abstract

Mineral dust aerosols have significant implications on the regional-hydroclimate, especially over the regions located downwind of dust sources. During the premonsoon season, much of South Asia is characterized by enhanced aerosol loading favored by the transport of mineral dust from the desert regions of West Asia/Northwest India. Vertically resolved backscatter measurements at dual polarization from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) are used to estimate the dust optical depth over the Indian region. Using a decade long data set of CALIOP observations, a shift in long-term trend of dust over the Northwest India, Indo-Gangetic Plain, and West Asia is demonstrated. The decreasing trend in dust loading over the Indian region reversed to increasing after 2013. The interannual variability in premonsoon dust optical depth over Northwest India is found to be associated with winter time rainfall. The interannual variation of tropospheric temperature anomalies over Northwest India did not show a direct correlation with mineral dust loading.