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Characterising the polluted dust layers reaching Himalayas: Size segregated chemical speciation, optical properties and mixing state of aerosol mixtures

EMSL Project ID


Atmospheric aerosols are composite of various emission sources and exist in a combination of individual particles (external mixing) as well as particle with more than one component (internal mixing). Specifically, aging of long-range transported dust layers in northern hemisphere at 1.5 to 4 km above surface is a dominant feature over North India during dry season. These layers can originate from arid regions of Middle East, Pakistan and India and traverse via westerlies across the hugely populated Indian Subcontinent, forming a complex mixture of mineral dust and anthropogenic aerosols, before reaching Himalayan region. Quantitatively, these mixed dust layers can have a radiative forcing of ~100 W/m2 in the atmosphere, and can impact the Indian climate via accelerating snowmelt and monsoon rainfall. However, uncertainties about the fundamental properties like complex refractive index and mixing state of the aerosol mixtures in these EALs still limits our understanding of EAL’s direct/indirect effect and snow darkening effects on regional hydroclimate. Through the proposed research we aim to address this critical barrier to progress in the field by better characterization of these elevated polluted dust layers in terms of the chemical speciation, morphology and mixing state of individual aerosol particles sampled at 3 km elevation over Indian Himalayas, using EMSL’s multi-modal chemical imaging and spectroscopy capabilities. Results from this work will enable improvements in remote sensing algorithms (like recently deployed EMIT satellite retrievals of dust characterisation) as well as in fine tuning the relevant aerosol modules in Earth system and climate prediction models and thereby reduce the uncertainties about polluted dust's impact on weather and hydroclimate over Indian sub-continent.

Project Details

Project type
Large-Scale EMSL Research
Start Date
End Date


Principal Investigator

Chandan Sarangi
Indian Institute of Technology, Madras


Rakesh K Hooda
Finnish Meteorological Institute