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Preprints
https://doi.org/10.5194/egusphere-2023-2654
https://doi.org/10.5194/egusphere-2023-2654
02 Jan 2024
 | 02 Jan 2024

Constraint of non-methane volatile organic compound emissions with TROPOMI HCHO observations and its impact on summertime surface ozone simulation over China

Shuzhuang Feng, Fei Jiang, Tianlu Qian, Nan Wang, Mengwei Jia, Songci Zheng, Jiansong Chen, Fang Ying, and Weimin Ju

Abstract. Non-methane volatile organic compounds (NMVOC), serving as crucial precursors of O3, have a significant impact on atmospheric oxidative capacity and O3 formation. However, both anthropogenic and biogenic NMVOC emissions remain subject to considerable uncertainty. Here, we extended the Regional multi-Air Pollutant Assimilation System (RAPAS) with the EnKF algorithm to optimize NMVOC emissions in China by assimilating TROPOMI HCHO retrievals. We also simultaneously optimize NOx emissions by assimilating in-situ NO2 observations to address the chemical feedback among VOC-NOx-O3. Furthermore, a process-based analysis was employed to quantify the impact of NMVOC emission changes on various chemical reactions related to O3 formation and depletion. NMVOC emissions exhibited a substantial reduction of 50.2 %, especially in forest-rich areas of central and southern China, revealing a prior overestimation of biogenic NMVOC emissions. The RAPAS significantly improved HCHO simulations, reducing biases by 75.7 %, indicating a notable decrease in posterior emission uncertainties. Moreover, the posterior NMVOC emissions significantly corrected the prior overestimation in O3 simulations, reducing biases by 49.3 %. This can be primarily attributed to a significant decrease in the RO2 + NO reaction rate and an increase in the NO2 + OH reaction rate in the afternoon, thus limiting O3 generation. Sensitivity analyses emphasized the necessity of considering both NMVOC and NOx emissions for a comprehensive assessment of O3 chemistry. This study enhances our understanding of the effects of NMVOC emissions on O3 production and can contribute to the development of effective emission reduction policies.

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Journal article(s) based on this preprint

02 Jul 2024
Constraining non-methane VOC emissions with TROPOMI HCHO observations: impact on summertime ozone simulation in August 2022 in China
Shuzhuang Feng, Fei Jiang, Tianlu Qian, Nan Wang, Mengwei Jia, Songci Zheng, Jiansong Chen, Fang Ying, and Weimin Ju
Atmos. Chem. Phys., 24, 7481–7498, https://doi.org/10.5194/acp-24-7481-2024,https://doi.org/10.5194/acp-24-7481-2024, 2024
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

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We developed a multi-air pollutant inversion system to estimate non-methane volatile organic...
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