Assessment of the vertical distribution of speciated aerosol absorption over South Asia using spaceborne LIDAR and ground-based observations

Abstract

Present study estimates the shortwave radiative effects of absorbing aerosols (dust and carbonaceous aerosols) over the Indian landmass using a synergy of spaceborne and ground-based observations. Vertical profiles of dust and total aerosols are estimated using the multi-year (2006-2017) observations from CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) over the Indian region. Pre-monsoon enhancement (March-May) in aerosol loading over the Indian region is significantly contributed (~56%) by the transported mineral dust at free tropospheric altitudes. Though, shortwave radiative effect due to dust in the atmosphere increases about three times from winter to pre-monsoon, at the top of the atmosphere (TOA) it causes cooling. Dust induced cooling reverses the positive radiative effect induced by non-dust aerosols at TOA over Indo-Gangetic Plains. Though the natural dust dominates the aerosol loading during pre-monsoon, anthropogenic dust contributes significantly (~65%) to the total dust loading during winter. Over Indo-Gangetic Plains, high aerosol warming (up to ~2 Kday − 1) observed within the planetary boundary layer (PBL) is mainly caused by carbonaceous aerosols (85%). The observed heating rates over the Indian region can have significant implications over regional climate, air quality, and changing precipitation patterns.