On the widespread enhancement in fine particulate matter across the Indo-Gangetic Plain towards winter

Ojha, N. and Sharma, A. and Kumar, M. and Girach, I. and Ansari, T.U. and Sharma, S.K. and Singh, N. and Pozzer, A. and Gunthe, S.S. (2020) On the widespread enhancement in fine particulate matter across the Indo-Gangetic Plain towards winter. Scientific Data, 10 (1). ISSN 2045-2322

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Abstract

Fine particulate matter (PM2.5, aerodynamic diameter ≤2.5 µm) impacts the climate, reduces visibility and severely influences human health. The Indo-Gangetic Plain (IGP), home to about one-seventh of the world's total population and a hotspot of aerosol loading, observes strong enhancements in the PM2.5 concentrations towards winter. We performed high-resolution (12 km × 12 km) atmospheric chemical transport modeling (WRF-Chem) for the post-monsoon to winter transition to unravel the underlying dynamics and influences of regional emissions over the region. Model, capturing the observed variations to an extent, reveals that the spatial distribution of PM2.5 having patches of enhanced concentrations (≥100 µgm-3) during post-monsoon, evolves dramatically into a widespread enhancement across the IGP region during winter. A sensitivity simulation, supported by satellite observations of fires, shows that biomass-burning emissions over the northwest IGP play a crucial role during post-monsoon. Whereas, in contrast, towards winter, a large-scale decline in the air temperature, significantly shallower atmospheric boundary layer, and weaker winds lead to stagnant conditions (ventilation coefficient lower by a factor of ~4) thereby confining the anthropogenic influences closer to the surface. Such changes in the controlling processes from post-monsoon to winter transition profoundly affect the composition of the fine aerosols over the IGP region. The study highlights the need to critically consider the distinct meteorological processes of west-to-east IGP and changes in dominant sources from post-monsoon to winter in the formulation of future pollution mitigation policies.

Item Type:
Journal Article
Journal or Publication Title:
Scientific Data
Additional Information:
Export Date: 24 April 2020
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1000
Subjects:
ID Code:
143537
Deposited By:
Deposited On:
29 Apr 2020 10:15
Refereed?:
Yes
Published?:
Published
Last Modified:
16 Sep 2020 06:16