Preprints
https://doi.org/10.5194/egusphere-2023-2723
https://doi.org/10.5194/egusphere-2023-2723
27 Nov 2023
 | 27 Nov 2023
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Aggravated surface O3 pollution primarily driven by meteorological variation in China during the early COVID-19 pandemic lockdown period

Zhendong Lu, Jun Wang, Yi Wang, Daven K. Henze, Xi Chen, Tong Sha, and Kang Sun

Abstract. Due to the lockdown during the COVID-19 pandemic in China from late January to early April in 2020, a significant reduction of primary air pollutants has been identified by satellite and ground observations. However, this reduction is in contrast with the increase of surface O3 concentration in many parts of China during the same period. The reasons for this contrast are studied here from two perspectives: emission changes and inter-annual meteorological variations. Based on top-down constraints of NOx emissions from TROPOMI measurements and GEOS-Chem model simulations, our analysis reveals that NOx and volatile organic compound (VOC) emission reductions as well as meteorological variations lead to 8 %, -3 %, and 1 % changes in O3 over North China, respectively. In South China, however, we find that meteorological variations cause ~30 % increases in O3, which is much larger than -1 % and 2 % changes due to VOC and NOx emission reductions, respectively, and the overall O3 increase is consistent with the surface observations. The higher temperature is the main reason that leads to the surface O3 increase in South China. Overall, inter-annual meteorological variations have a larger impact than emission reductions on the aggravated surface O3 pollution in China during the early lockdown period of COVID-19 pandemic.

Zhendong Lu, Jun Wang, Yi Wang, Daven K. Henze, Xi Chen, Tong Sha, and Kang Sun

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
Zhendong Lu, Jun Wang, Yi Wang, Daven K. Henze, Xi Chen, Tong Sha, and Kang Sun
Zhendong Lu, Jun Wang, Yi Wang, Daven K. Henze, Xi Chen, Tong Sha, and Kang Sun

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Short summary
In contrast with the past work showing the reduction of emission as the dominant factor for nation-wide increase of surface O3 during the lockdown in China, this study finds that the variation in meteorology (temperature and other parameters) plays a more important role. This result is obtained through sensitivity simulations using a chemical transport model constrained by satellite (TROPOMI) and calibrated with surface observation.