Observationally Constrained Modeling of Peroxy Radical During an Ozone Episode in the Pearl River Delta Region, China

doi:10.1029/2022JD038279

	Wang, Jun 1,2,3; Zhang, Yanli1,2,4 ; Zhao, Weixiong 5; Wu, Zhenfeng 1,2,3; Luo, Shilu 1,2,3; Zhang, Huina 1,2,3; Zhou, Huaishan 1,2,3; Song, Wei 1,2; Zhang, Weijun ; Wang, Xinming1,2,3,4
	Observationally Constrained Modeling of Peroxy Radical During an Ozone Episode in the Pearl River Delta Region, China
Source Publication	JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES
ISSN	2169-897X
	2023-06-27
Volume	128 Issue:12 Pages:17
DOI	10.1029/2022JD038279
Language	英语
WOS Research Area	Meteorology & Atmospheric Sciences
Abstract	Peroxy radicals (RO2* = HO2 + RO2) play key roles in forming secondary air pollutants such as ozone, yet model underprediction of RO2* is a challenging radical closure problem. In this study, RO2* were measured by a dual-channel peroxy radical chemical amplification system during an ozone episode in October 2018 at an urban site in the Pearl River Delta region, China. The box model based on the Master Chemical Mechanism severely underpredicted RO2* levels, particularly at night and under high nitric oxide (NO) conditions. The observed-to-modeled ratio of RO2* increased from similar to 3 under 1 ppbv NO to & SIM;46 under >10 ppbv NO with a missing RO2* source up to 5.8 ppbv hr(-1). Observation data were used to constrain model predictions, and the results reveal that constraining nitrous acid (HONO) or glyoxal/methylglyoxal could not improve predictions, while constraining nitrate radicals (NO3) or other oxygenated volatile organic compounds (OVOCs), particularly phenolic compounds and improvements in their gas-phase mechanisms, could more effectively increase model-simulated RO2* concentrations. When OVOCs, NO3, and HONO were constrained, the simulated RO2* concentrations increased to the greatest extent with an observed-to-modeled RO2* ratio of 1.9 during the day and 1.3 at night, mainly due to the interaction between OVOCs and NO3 radicals. As the underestimated NO3 levels and the unmeasured reactive organic gases, as well as their unknown oxidation mechanisms, are among the major reasons for the underestimation of RO2, upgraded atmospheric chemistry involving more OVOC species and more accurate NO3 would improve model-simulated RO2 concentrations, especially during nighttime. Plain Language Summary Peroxy radicals (RO2* = HO2 + RO2), including hydroperoxy radicals (HO2) and organic peroxy radicals (RO2), are mainly formed by atmospheric oxidative degradation of trace gases, such as formaldehyde, carbon monoxide (CO) and volatile organic compounds (VOCs). They are important intermediates for the tropospheric forming secondary air pollutants, yet model underprediction of RO2* is a challenging radical closure problem. Here, we conducted a field campaign during an ozone episode in October 2018 at an urban site in the Pearl River Delta region and revealed that RO2* concentrations simulated by the AtChem2-MCM were much lower than those observed, particularly at nighttime and under high nitric oxide conditions. We found that using the observations of oxygenated volatile organic compounds (OVOCs) and nitrate radicals to constrain the model could more effectively reduce the gap between the simulated and observed RO2* radicals. Our results highlight that, more attention should be given to OVOCs that have not been measured or whose oxidation mechanisms are not well understood, but can be photolyzed or oxidized to form RO2, such as phenolic compounds, for the in-depth understanding of tropospheric RO2 chemistry.
WOS ID	WOS:001022730700001
Indexed By	SCI
Citation statistics
Document Type	期刊论文
Identifier	http://ir.gig.ac.cn/handle/344008/74464
Collection	有机地球化学国家重点实验室
Corresponding Author	Zhang, Yanli; Wang, Xinming
Affiliation	1.Chinese Acad Sci, Guangzhou Inst Geochem, State Key Lab Organ Geochem, Guangdong Key Lab Environm Protect & Resources Uti, Guangzhou, Peoples R China 2.Chinese Acad Sci, Ctr Excellence Deep Earth Sci, Guangzhou, Peoples R China 3.Univ Chinese Acad Sci, Beijing, Peoples R China 4.Chinese Acad Sci, Inst Urban Environm, Ctr Excellence Reg Atmospher Environm, Xiamen, Peoples R China 5.Chinese Acad Sci, Anhui Inst Opt & Fine Mech, Lab Atmospher Phys Chem, Hefei, Peoples R China
Recommended Citation GB/T 7714	Wang, Jun,Zhang, Yanli,Zhao, Weixiong,et al. Observationally Constrained Modeling of Peroxy Radical During an Ozone Episode in the Pearl River Delta Region, China[J]. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES,2023,128(12):17.
APA	Wang, Jun.,Zhang, Yanli.,Zhao, Weixiong.,Wu, Zhenfeng.,Luo, Shilu.,...&Wang, Xinming.(2023).Observationally Constrained Modeling of Peroxy Radical During an Ozone Episode in the Pearl River Delta Region, China.JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES,128(12),17.
MLA	Wang, Jun,et al."Observationally Constrained Modeling of Peroxy Radical During an Ozone Episode in the Pearl River Delta Region, China".JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 128.12(2023):17.

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