2018年中国中东部地区臭氧浓度分布的时空特征

Spatial and temporal variations of ozone concentrations in the mid‐east part of China in 2018

近几年,受人为排放的挥发性有机物逐年增加和大气中PM2.5浓度逐年降低的影响,近地面的O_(3)已成为影响我国夏季空气质量的首要污染物,全国很多地区每年5月至9月会出现O_(3)污染超标的现象和O_(3)大范围蔓延的趋势.利用2018年逐时的O_(3)浓度分析场数据对我国中东部尤其是京津冀、长三角和珠三角地区O_(3)浓度的时空变化趋势进行研究.结果表明,随着时间变化,月平均O_(3)浓度在京津冀地区呈倒“V”型,在长三角和珠三角地区呈“M”型,这是因为O_(3)生成与地表接受的短波辐射通量有较好的线性关系.在京津冀地区6月太阳辐射强度最大且云量较小,因此O_(3)污染严重,O_(3)超标天数接近一半;而长三角和珠三角地区在7月受雨季的影响,云量较大,因此O_(3)月平均浓度相对较小,月平均浓度变化呈现出“M”型.而在一天内O_(3)浓度在上午逐渐上升,午后达到最大且稍滞后于地表所受到的短波辐射通量的日变化.

Affected by increasing emissions of volatile organic compounds(VOCs)and decreasing PM2.5 in atmosphere,ozone(O_(3))has become the chief pollutant in summer during recent years in China.From May to September each year,O_(3) pollution goes above the acceptance level and spreads widely in many parts of China.In this study,we investigated spatial and temporal trends of O_(3) concentration in the central and eastern China,especially in the Beijing⁃Tianjin⁃Hebei,Yangtze River Delta and Pearl River Delta regions,using the analysis dataset of the hourly O_(3) concentration in 2018.The results indicated that monthly O_(3) concentration showed the pattern of inverted"V"in the Beijing⁃Tianjin⁃Hebei region and"M"in the Yangtze River Delta and the Pearl River Delta.The generation of O_(3) was highly related to solar radiation.In the Beijing⁃Tianjin⁃Hebei region,the pollution reached its peak in June with the maximum solar radiation intensity of the year which was caused by less cloud fraction,when the days of over⁃standard daily average concentration reached the highest level,accounting for approximately half month.While in the Yangtze River Delta and the Pearl River Delta,affected by larger cloud fraction in the rainy seasons,the monthly average of O_(3) concentration was relatively low in July,resulting in the decreasing part in the bimodal pattern.In the daytime,O_(3) concentration changed as the surface short flux changes with 1~2 hours lag.