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Using a New Top-Down Constrained Emissions Inventory to Attribute the Previously Unknown Source of Extreme Aerosol Loadings Observed Annually in the Monsoon Asian Free Troposphere
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  • Shuo Wang,
  • Jason Blake Cohen,
  • Weizhi Deng,
  • Qin Kai,
  • Jianping Guo
Shuo Wang
School of Atmospheric Sciences, Sun Yat-Sen University
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Jason Blake Cohen
School of Atmospheric Sciences, Sun Yat-Sen University

Corresponding Author:[email protected]

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Weizhi Deng
School of Atmospheric Sciences, Sun Yat-Sen University
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Qin Kai
China University of Mining and Technology
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Jianping Guo
State Key Laboratory of Severe Weather, Chinese Academy of Meteorological Sciences
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Abstract

The contribution of biomass burning to the total aerosol loading over Monsoon Asia is both significant while also continuing to increase in recent decades. To better match the spatio-temporal distribution of aerosols and trace gasses observed in the free troposphere, this work applied a 3-D constrained emission inventory based on top-down remotely sensed NO2 measurement to investigate the most extreme of the annually occurring biomass burning seasons in Monsoon Asia. In 2016 this constituted an extreme event observed over a 6-day period covering millions of square kilometers, including over regions which are typically in the rainy phase of the Monsoon at this time. The results are shown to be consistent with respect to TRMM precipitation, AERONET measurements, MODIS AOD, MOPITT CO, and reanalysis meteorology, over both the biomass burning source as well as the millions of square kilometers downwind both to the East and to the Southwest. Reproducing the observed long-range transport pattern requires the time of biomass burning to be increased, regions not previously identified as burning to be actual source regions, and the emissions of BC to be 6.6 to 11.9 time larger than current inventories. The underlying mechanism for this long-range transport involves a new 3-D pathway that can occur during the transition from the North to the South Monsoon. The results are also consistent with the new idea that large loadings of BC in the lower free troposphere may significantly affect the meteorological field and the overall vertical distribution of aerosols in the tropical troposphere.
Jul 2021Published in Earth's Future volume 9 issue 7. 10.1029/2021EF002167