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Carbonaceous Aerosol From Open Burning and its Impact on Regional Weather in South Asia

Category: Air Pollution Modeling

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DOI: 10.4209/aaqr.2019.03.0146
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To cite this article:
Singh, P., Sarawade, P. and Adhikary, B. (2020). Carbonaceous Aerosol From Open Burning and its Impact on Regional Weather in South Asia. Aerosol Air Qual. Res., doi: 10.4209/aaqr.2019.03.0146.

Prashant Singh1,2, Pradip Sarawade 1, Bhupesh Adhikary 2

  • 1 Department of Physics, University of Mumbai, Mumbai 400098, India
  • 2 International Centre for Integrated Mountain Development (ICIMOD), Khumaltar, Lalitpur, Nepal

Highlights

  • Long term emissions of open biomass burning (OBB) are analyzed for South Asia.
  • OBB emitted carbonaceous aerosol (CA) strongly affect radiative forcing.
  • OBB emitted CA reduces the dispersion of pollutant at the regional scale.

Abstract

Seasonal open biomass burning contributes to significant carbonaceous aerosol loading over South Asia. This study analyzes long-term trends in emissions in two hotspot regions, Myanmar and Punjab, using data from the Global Fire Emissions Database (GFED4s) and Fire Inventory (FINN) from the National Center for Atmospheric Research (NCAR). Analysis of emissions during active fire seasons reveals that Punjab emissions increase by approximately 83-106% compared to anthropogenic emissions, while Myanmar emissions increase by 2338-3054% based on the FINN model results. We examine the impact of carbonaceous aerosol from open biomass burning on regional weather by Weather Research and Forecasting model coupled with the Chemistry (WRF-CHEM). We examine results from a year-long simulation during the post-monsoon and pre-monsoon periods when active fires are reported. Results show that carbonaceous aerosol from open biomass burning is lofted up to 3-5 km vertically; horizontally, these aerosol rises up to 850 hPa from the surface and disperse throughout South Asia. Radiative forcing calculations suggest changes up to -6.14 W/m2 at the surface and -0.50 W/m2 at the top of the atmosphere over Punjab and -42.76 W/m2 at the surface and -1.91 W/m2 at the top of the atmosphere over Myanmar. Our results indicate that carbonaceous aerosol (BC + OC together) also reduce surface temperature similar to black carbon (BC) despite the scattering effects of organic carbon. The results also show that surface temperature decreased by 2K, relative humidity changed by 8%, and planetary boundary layer changed up to 600m with open biomass burning. Changes in precipitation patterns and volume due to carbonaceous aerosol from open biomass burning were negligible when considering only the direct radiative feedback.

Keywords

South Asia Biomass burning Carbonaceous aerosol WRF-Chem


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