Mineral dust characterization over the Himalayan cryosphere using space-borne lidar depolarization observations

Abstract

Present study represents the first time quantitative characterization of mineral dust aerosols based on depolarization observations of the space-borne lidar CALIOP (Cloud Aerosol Lidar with Orthogonal polarization) over the Himalayas. Dust loading is dominant during pre-monsoon season and weak during winter/summer monsoon seasons. Average dust extinction coefficient over a period of 11 years (2006 - 2017) shows regionally and seasonally distinct characteristics over the Himalayas. Dust loading is observed highest over the Mid Himalayas. Over the mid-Himalayas almost 10 fold increase is observed from winter to pre-monsoon. Dust aerosols mostly occur in the form of polluted dust (dust mixed with anthropogenic aerosols) during pre-monsoon season. The contribution of polluted dust to the total aerosols over western, mid and eastern Himalayas are estimated to be 63%, 67% and 57% respectively. A significant amount of dust aerosols (12.5 mgm−2 day−1 over mid Himalayas) are deposited through dry deposition over the Himalayas which is capable of producing enhanced snow melting and reduction in snow cover over the Himalayan cryosphere.