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.

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

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2654', Anonymous Referee #2, 26 Jan 2024
  • RC2: 'Comment on egusphere-2023-2654', Anonymous Referee #1, 24 Feb 2024
Shuzhuang Feng, Fei Jiang, Tianlu Qian, Nan Wang, Mengwei Jia, Songci Zheng, Jiansong Chen, Fang Ying, and Weimin Ju

Data sets

Non-methane volatile organic compound emissions over China estimated using TROPOMI HCHO retrievals Shuzhuang Feng and Fei Jiang https://doi.org/10.5281/zenodo.10079006

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

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Short summary
We developed a multi-air pollutant inversion system to estimate non-methane volatile organic compound (NMVOC) emissions using TROPOMI formaldehyde retrievals. We found that the inversion significantly improved formaldehyde simulations and reduced NMVOC emission uncertainties. The optimized NMVOC emissions effectively corrected the overestimation of O3 levels, mainly by decreasing the rate of the RO2 + NO reaction and increasing the rate of the NO2 + OH reaction.