Which aerosol type dominate the impact of aerosols on ozone via changing photolysis rates?

Jinhui Gao; Ying Li; Zhouqing Xie; Lili Wang; Bo Hu; Fangwen Bao

doi:10.1016/j.scitotenv.2022.158580

Which aerosol type dominate the impact of aerosols on ozone via changing photolysis rates?

Sci Total Environ. 2023 Jan 1:854:158580. doi: 10.1016/j.scitotenv.2022.158580. Epub 2022 Sep 6.

Authors

Jinhui Gao¹, Ying Li², Zhouqing Xie³, Lili Wang⁴, Bo Hu⁴, Fangwen Bao⁵

Affiliations

¹ Plateau Atmosphere and Environment Key Laboratory of Sichuan Province, School of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu, China; Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China.
² Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China. Electronic address: liy66@sustech.edu.cn.
³ Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China.
⁴ State Key Laboratory of Atmosphere Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China.
⁵ Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, China; Center for the Oceanic and Atmospheric Science at SUSTech (COAST), Southern University of Science and Technology, Shenzhen, China.

PMID: 36075440
DOI: 10.1016/j.scitotenv.2022.158580

Abstract

The impact of aerosols on ozone via influencing photolysis rates is a combined effect of absorbing aerosols (AA) and scattering aerosols (SA). However, AA and SA show different optical properties and influence photolysis rates differently, which then cause different impacts on ozone. Till now, the dominate factor is disconfirmed, which is largely due to the impact of SA on ozone not reaching to a consistent conclusion. In this study, the WRF-Chem model was implemented to simulate the air pollutants over the North China Plain (NCP). The impacts of AA and SA on ozone via influencing photolysis rates were quantitatively isolated and analyzed. Our results also demonstrated the decreasing effect of AA on ozone within planet boundary layer (PBL) which is consistent with the conclusions of previous studies. But for SA, it decreased the ozone chemical contribution (CHEM) near surface but increased which in the upper layers of PBL, that enlarge the ozone vertical gradients. In this case, more vertical exchanges of ozone would occur with the effect of vertical mixing motion of atmosphere, then the opposite CHEM variations were counteracted with each other and finally led to very slight changes in ozone within PBL. Thus, it can be summarized that AA dominate this impact of aerosols on ozone. Reducing AA could cause a general increase in ozone (ΔO₃) over the NCP. Based on the aerosol levels of this case, ΔO₃ would be seen over 86 % of the areas in the NCP when reducing AA by 3/4 and ΔO₃ was more significant in the megacities. Our study highlights the different relationships between ozone and aerosol types, which suggests that more attentions should be paid on aerosol types, especially AA, when making the synergetic control strategy of aerosols and ozone in China.

Keywords: Absorbing aerosols; Ozone pollution; Photolysis rates; Scattering aerosols; WRF-Chem.