摘要
本研究首先基于地面观测数据,分析了2015—2018年华北地区春季臭氧污染特征,发现春季臭氧污染程度仅次于夏季,其中2015和2017年的臭氧日最大8 h(MDA8),最大值均出现在春季(主要发生在5月),并且多次发生大范围臭氧超标事件。进一步利用大气化学输送模式WRF-CMAQ,结合敏感性数值实验,揭示天然源排放对2015—2018年华北地区春季平均臭氧MDA8浓度贡献为3.45~5.38μg·m^(-3),在臭氧重污染时,其贡献超过10μg·m^(-3)(约为7%)。最后,针对华北地区发生的3次长时间(持续时间一周)大范围臭氧污染事件,阐明影响臭氧生消的物理化学过程具有明显的垂向变化特征。具体而言,对于臭氧的生成和累积,近地面主要受垂向扩散影响,其次是光化学反应;从近地面到边界层顶的臭氧生成主要依赖化学反应;垂向扩散和水平输送则是自由对流层中臭氧生成的主要控制因素。考虑到世界卫生组织(WHO)2021年提出的臭氧长期(6个月)标准,厘清华北地区春季臭氧污染的来源及成因,可为中国未来臭氧达到WHO新标准提供重要的科学依据。
Recently, the ozone pollution becomes severe, and many researchers have tried to elucidate the formation mechanism and sources of ozone pollution. Observations indicate that ozone pollution in spring occurs sometimes, however, the governing mechanism has not yet to be clear. In this study, we first characterize the ozone pollution in spring 2015—2018 in North China based on observed data. The results indicate that the severity of ozone pollution in spring is close to that in summer, and the largest values of maximum daily 8-hr ozone(MDA8) ozone in 2015 and 2017 occur in spring(mainly in May). Meanwhile, a number of widespread ozone pollution events occur in spring over North China as well. Secondly, by utilizing the atmospheric numerical model WRF-CMAQ and designing numerical sensitivity experiments, we reveal that the contributions of biogenic emissions on ozone concentration is on ave-rage of 3.45~5.38 μg·m^(-3)in spring over North China during 2015—2018, which may reach more than 10 μg·m^(-3)(7%) during the severe ozone pollution. At the end, focusing on the three long-lasting(one week) ozone pollution events spreading a large area in North China, we illustrate that obviously vertical modulation feature emerges in terms of the physical and chemical processes governing the ozone formation and sink. Specifically, for the ozone formation and accumulation, the vertical diffusion plays the dominant role at surface level, followed by the photochemical reaction;from surface to the top of boundary layer, the chemical reaction is the primary factor in ozone formation;vertical diffusion and horizontal advection then become the major process over the free troposphere. Considering that World Health Organization(WHO) has released a new guideline on long-term(six-month) exposure to ozone concentration, the elucidation of ozone sources and factors in spring North China may provide a vital scientific basis for China to achieve the new guideline in future.
作者
李超群
马铭晨
严非凡
程文轩
寇文彬
高阳
Li Chaoqun;Ma Mingchen;Yan Feifan;Cheng Wenxuan;Kou Wenbin;Gao Yang(The Key Laboratory of Marine Environment and Ecology,Ministry of Education,Ocean University of China,Qingdao 266100,China)
出处
《中国海洋大学学报（自然科学版）》
CAS
CSCD
北大核心
2022年第S01期1-11,共11页
Periodical of Ocean University of China
基金
中央高校基本科研业务费专项(201941006)资助。
关键词
臭氧污染
华北地区
数值模式
天然源
过程分析
ozone pollution
North China
numerical modeling
biogenic emissions
process analysis
作者简介
李超群(1996-),女,硕士生。E-mail:1195258723@qq.com;通讯作者:高阳,E-mail:yanggao@ouc.edu.cn。
