The optically thick aerosol layer along the southern edge of the Himalayas, over the Indo-Gangetic Plains, has been a subject of investigations relating to its impacts on the South Asian summer monsoon and regional climate. Specifically, prior to the onset of the summer monsoon, the region is strongly influenced by mineral dust transport, originating from Southwest Asian deserts and from as far as the Arabian Peninsula. Mixed with anthropogenic pollution, mineral dust forms a widespread vertically extended haze against the southern slopes of the Himalayas. Episodic dust plumes are also advected over the elevated Himalayas, sometimes leading to dust-capped snow and ice surfaces.
This talk will cover the characterization of aerosols over the Gangetic and sub-Himalayan region from ground-based and satellite observations, focusing on the pre-monsoon season. An assessment of the regional aerosol loading in terms of optical properties, vertical distribution, daytime variability and radiative effect, will be presented, focusing on the pre-monsoon season. We also examined emerging patterns and trends in aerosol loading over southern Asia, including over source and downwind regions, from satellite and ground-based datasets. Additionally, ongoing investigation of possible impacts of aerosol deposition, particularly mineral dust, on the reduction of snow albedo in the Himalayas will be presented, using satellite spectral reflectivity measurements. The overall objective of this observational-based study is towards a better understanding of regional aerosol loading and associated effects on the monsoonal climate of southern Asia.