青藏高压系统对川渝春夏臭氧污染的影响机制

Mechanism of Qinghai-Tibet high pressure system on spring and summer ozone pollution over Sichuan-Chongqing area

为研究青藏高压系统对川渝地区春夏季臭氧(O3)污染的影响机制,对2015~2018年每年4~9月的中国气象局高空全要素填图数据(Micaps PLOT High)、川渝14个城市的国控环境监测站点O3监测数据及气象台站数据进行了研究分析.结果表明:O3浓度的高低与青藏高压中心位置分布的状况和数量密切相关,中心分布越密集、出现的极值区域越多和中心个数越多时,同期地表温度越高,O3浓度越高(尤其是中心位置出现在100°E和28°N的频数越多,地表温度越高,导致较多O3极值的出现).对比分析同年逐月与逐年同月高压脊线南北偏移情况对O3浓度的影响,发现高压脊线越往北跳,对应日照时数越长,O3浓度越高.综合分析高压中心和高压脊线对川渝地区O3影响的共同作用,发现高压中心和高压脊线分别主要通过控制地表温度和日照时数来影响O3浓度,且同一时段,二者对O3浓度影响的效果和程度也存在差异,有时对O3浓度的增加表现为协同作用,有时为拮抗作用.

In order to study the mechanism of Qinghai-Tibet high pressure system on spring and summer ozone(O3)pollution over Sichuan-Chongqing area,the Micaps PLOT High upper-air total factor data,national environmental monitoring station O3 observation data and meteorological station data of 14 cities from April to September of 2015 to 2018 were analyzed.Results showed that O3 concentration was closely related to the distribution and quantity of the central position of Qinghai-Tibet high pressure system.The denser the high-pressure center,the more extreme areas and the number of centers,the higher the surface temperature and O3 concentration in the same period.Especially the frequency of the center appeared around 100°E and 28°N,the surface temperature was higher,led to the emergence of more extreme high concentration of O3.Compared and analyzing the influence of the north-south migration of the high-pressure ridge on O3 concentration during different years and months,it was found that the northward migration of high-pressure ridge leaded to longer sunshine duration and higher O3 concentration.The combined effects of high-pressure center and ridge line on O3 over Sichuan-Chongqing area were analyzed as well,which showed that high-pressure center and high-pressure ridge affect the O3 concentration mainly by controlling the surface temperature and sunshine duration,respectively.At the same time,the effect and degree of the two effects on O3 concentration were also different(i.e.,sometimes the increase of O3 concentration showed synergistic effect,while sometimes antagonistic effect).