Aerosol Properties and Radiative Effects in South Asia

Aerosols over South Asia arise from a mix of natural sources such as desert dust and sea salt, and anthropogenic emissions from industry, transport and biomass burning. Their physical and chemical properties – including size distribution, composition and hygroscopicity – govern how they scatter and absorb solar and terrestrial radiation. High aerosol optical depths during the pre-monsoon and winter seasons lead to marked surface dimming, while absorption by black carbon and dust layers heats the atmosphere and alters stability. These effects influence the regional monsoon through mechanisms such as the elevated heat pump, modify cloud formation and precipitation patterns, and have far-reaching consequences for air quality, human health and agricultural productivity. Understanding spatial variations in aerosol loading and radiative impacts is critical for climate projection, air-quality management and adaptation strategies across the densely populated Indo-Gangetic Plain and adjacent oceanic outflows.

Research from Nature Portfolio

Long-term analyses of pre-monsoon dust over the Indian subcontinent reveal a 10–20% decline in dust loading between 2000 and 2015. This trend has been attributed to increased pre-monsoon rainfall enhancing wet scavenging and to a slowing of large-scale circulation over northwestern India. The reduced dust influx modifies the intensity of the elevated heat pump mechanism, with implications for monsoon onset and rainfall distribution. Changes in aerosol composition and vertical distribution also alter the direct radiative balance, suggesting evolving feedbacks between aerosol trends and regional climate variability.

Aerosol Properties and Radiative Effects in South Asia publication trend

The graph below shows the total number of articles in aerosol properties and radiative effects in south asia across all publications each year (not limited to Nature Index journals).

Technical terms

Aerosol optical depth (AOD): A dimensionless measure of the attenuation of solar radiation by aerosols in a vertical column.
Single scattering albedo (SSA): The fraction of light extinction attributable to scattering rather than absorption by particles.
Radiative forcing: The net change in energy flux at a given atmospheric level due to a perturbing agent, expressed in W m⁻².
Direct radiative forcing: The immediate alteration of radiative fluxes by aerosol scattering and absorption without mediation by clouds.
Top-of-the-atmosphere (TOA): The boundary at which incoming solar and outgoing terrestrial radiation are balanced and quantified.

References

1. Declining pre-monsoon dust loading over South Asia: Signature of a changing regional climate. Scientific Reports (2017).
2. Aerosol demasking enhances climate warming over South Asia. npj Climate and Atmospheric Science (2023).
3. Dipole pattern in aerosol-induced atmospheric warming trends over the Indian subcontinent in the last two decades. Environmental Research Letters (2025).
4. 3D assimilation and radiative impact assessment of aerosol black carbon over the Indian region using aircraft, balloon, ground-based, and multi-satellite observations. Atmospheric Chemistry and Physics (2023).