气候变化领域集成服务门户(CCPortal): Changing ozone sensitivity in the South Coast Air Basin during the COVID-19 period

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DOI	10.5194/acp-22-12985-2022
	Changing ozone sensitivity in the South Coast Air Basin during the COVID-19 period
	Schroeder, Jason R.; Cai, Chenxia; Xu, Jin; Ridley, David; Lu, Jin; Bui, Nancy; Yan, Fang; Avise, Jeremy
发表日期	2022
ISSN	1680-7316
EISSN	1680-7324
起始页码	12985
结束页码	13000
卷号	22 期号:19 页码:16
英文摘要	The South Coast Air Basin (SoCAB), which includes the city of Los Angeles and is home to more than 15 million people, frequently experiences ozone (O-3) levels that exceed ambient air quality standards. While strict regulation of O-3 precursors has dramatically improved air quality over the past 50 years, the region has seen limited improvement in O-3 over the past decade despite continued reductions in precursor emissions. One contributing factor to the recent lack of improvement is a gradual transition of the underlying photochemical environment from a VOC-limited regime (where VOC denotes volatile organic compound) towards an NOx- limited one. The changes in human activity prompted by COVID-19-related precautions in spring and summer of 2020 exacerbated these existing changes in the O-3 precursor environment. Analyses of sector-wide changes in activity indicate that emissions of NOx decreased by 15 %-20 % during spring (April-May) and by 5 %-10 % during summer (June-July) relative to expected emissions for 2020, largely due to changes in mobile-source activity. Historical trend analysis from two indicators of O-3 sensitivity (the satellite HCHO/NO2 ratio and the O-3 weekend/weekday ratio) revealed that spring of 2020 was the first year on record to be on average NOx-limited, while the transitional character of recent summers became NOx-limited due to COVID-19-related NOx reductions in 2020. Model simulations performed with baseline and COVID-19-adjusted emissions capture this change to an NOx-limited environment and suggest that COVID-19-related emission reductions were responsible for a 0-2 ppb decrease in O-3 over the study period. Reaching NOx-limited territory is an important regulatory milestone, and this study suggests that deep reductions in NOx emissions (in excess of those observed in this study) would be an effective pathway toward long-term O-3 reductions.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000865489200001
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/273104
推荐引用方式 GB/T 7714	Schroeder, Jason R.,Cai, Chenxia,Xu, Jin,et al. Changing ozone sensitivity in the South Coast Air Basin during the COVID-19 period[J],2022,22(19):16.
APA	Schroeder, Jason R..,Cai, Chenxia.,Xu, Jin.,Ridley, David.,Lu, Jin.,...&Avise, Jeremy.(2022).Changing ozone sensitivity in the South Coast Air Basin during the COVID-19 period.ATMOSPHERIC CHEMISTRY AND PHYSICS,22(19),16.
MLA	Schroeder, Jason R.,et al."Changing ozone sensitivity in the South Coast Air Basin during the COVID-19 period".ATMOSPHERIC CHEMISTRY AND PHYSICS 22.19(2022):16.