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21st Century Change in Global Small-Size Aerosols from Combustion Emissions

Lee, Meemong and Worden, John R. and Bucholz, Rebecca and Worden, Helen and Park, Mijeong and Wang, Yuan and Yang, Jiani and Witek, Marcin and Su, Hui and Byrne, Brendan and Miyazaki, Kazu and Jiang, Jonathan H. (2021) 21st Century Change in Global Small-Size Aerosols from Combustion Emissions. . (Unpublished)

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Changes in aerosol optical depth, both positive and negative, are observed across the globe during the 21rst Century. However, attribution of these changes to specific sources is largely uncertain as there are multiple contributing natural and anthropogenic sources that produce aerosols either directly or through secondary chemical reactions. Here we show that satellite-based changes in small-mode AOD between 2002 and 2019 observed in data from MISR can primarily be explained by changes, either directly or indirectly, in combustion emissions. We quantify combustion emissions using MOPITT total column CO observations and the adjoint of the GEOS-Chem global chemistry and transport model. The a priori fire emissions are taken from the Global Fire Emission Data base with small fires (GFED4s) but with fixed a priori for non-fire emissions. Aerosol precursor and direct emissions are updated by re-scaling them with the monthly ratio of the CO posterior to prior emissions. The correlation between modeled and observed AOD improves from a mean of 0.15 to 0.81 for the four industrial regions considered and from 0.52 to 0.75 for the four wildfire-dominant regions considered. Using these updated emissions in the GEOS-Chem global chemistry transport model, our results indicate that surface PM2.5 have declined across many regions of the globe during the 21rst century. For example, PM2.5 over China has declined by ~30% with smaller fractional declines in E. USA and Europe (from fossil emissions) and in S. America (from fires). These results highlight the importance of forest management and cleaner combustion sources in improving air-quality.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription Paper
Lee, Meemong0000-0002-8797-8209
Worden, John R.0000-0003-0257-9549
Worden, Helen0000-0002-5949-9307
Wang, Yuan0000-0001-6657-8401
Witek, Marcin0000-0002-0675-4458
Su, Hui0000-0003-1265-9702
Byrne, Brendan0000-0003-0619-3045
Miyazaki, Kazu0000-0002-1466-4655
Jiang, Jonathan H.0000-0002-5929-8951
Additional Information:© 2021. All rights reserved. California Institute of Technology, government sponsorship acknowledged. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology under a contract with National Aeronautics and Space Administration (80NM0018D0004). We acknowledge the funding support by the JPL Strategic Advances in Air Quality Research and Technology Development. We also thank the support from NASA ROSES ACMAP and TASNPP programs. ©2021. All rights reserved. Data Statement. The satellite data used in this study are publicly available for download at NASA website In addition, websites available for data download include: MOPITT level 2 data products:; MISR level 2 data products: All data underlying this article are available in the article. For additional questions regarding the data sharing and data assimilation system, please contact the corresponding author at Author contributions. J.W., M.L., and J.J. designed the research; M. L performed the CO flux inversion, AOD model simulation, and comparison of the modeled AOD with the MISR-AOD. J.W and M.L wrote the manuscript and the co-authors assisted in manuscript preparation. Several co-authors are also involved in evaluating the results and preparing the data needed for this research. These include B.B. for ATom CO comparison, M. W. for MISR AOD mode properties, and K. M. for OH, SO₂, and NO_x data products.
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Record Number:CaltechAUTHORS:20210607-115056829
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:109425
Deposited By: George Porter
Deposited On:10 Jun 2021 21:34
Last Modified:16 Nov 2021 19:36

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