深圳市秋季大气臭氧立体分布特征

Vertical distribution characteristics of ozone pollution in Shenzhen in autumn

利用大气O3探测激光雷达在深圳市东部生态区和西部城区同步开展垂直观测,探究了2018年深圳市O3立体分布在秋季光化学污染活跃期至冬季非活跃期的演变过程.结果表明:光化学反应活跃的10月,东部地面O3浓度相对于西部地面高出约128%;地面向上至450m,O3浓度在东部生态区发生快速降低,而在西部城区由于存在"滴定效应",O3浓度随高度升高而升高;450m-2km,东、西部O3浓度均随高度升高而降低,西部城区O3浓度水平超过东部生态区约30%;2km以上高空,东、西部O3浓度趋同(70μg/m^3),并保持稳定,为具深圳市秋季O3污染过程提供了较高的大气背景浓度.高污染期间,深圳市大气边界层内O3浓度变化较为一致,西部高空的O3区域传输作用更加显著.秋季至冬季光化学反应逐渐减弱,深圳市O3浓度的水平和垂直空间差异逐渐减小,冬季的深圳市O3污染基本受大气背景控制.

Simultaneous O3 observation was carried out in both the eastern natural ecological zone and the western urban living area in Shenzhen from the autumn with high photochemical activity to the winter with low photochemical activity in 2018,and then the evolution process of O3 was explored and discussed.The results showed that during October,the O3 concentration observed in the eastern site was 128%higher than that in the western site near the ground.From the ground to an elevation of 450 m,the O3 concentration in the east decreased.Conversely,due to the titration effect occurring in the west,the concentration of O3 increased in proportion to the elevation up to 450m.From 450 m to 2km,the O3 concentration decreased at both sites,with the O3 concentration in the western area being about 30%higher than that in the eastern area.The O3 concentration above 2km was generally stable and can be regarded as the background concentration(~70μg/m^3),providing a high regional background concentration for the autumn O3 pollution in Shenzhen.Analysis of high pollution process showed that the O3 pollution variation was consistent within the atmospheric boundary layer in Shenzhen,indicating that O3 pollution was significantly affected by regional transport.The transport of O3 at the high altitudes in the western area was more prominent.From autumn to winter,the O3 concentration decreased continuously due to the weakened photochemical reactions,and the horizontal and vertical variation of O3 concentration also decreased in Shenzhen.The O3 pollution level was essentially controlled by the regional background inwinter in Shenzhen.