差分吸收激光雷达用于探测天津市夏秋季臭氧垂直分布特征

Observation of vertical distribution of ozone based on differential absorption lidar during summer and autumn in Tianjin

结合差分吸收臭氧激光雷达与近地面臭氧监测,对天津市2018年6月23日至9月28日期间的臭氧污染垂直分布特征进行了长期观测。结果显示,近地面与300 m高度处的臭氧浓度的变化趋势具有较高的一致性,而随着高度的增加,臭氧浓度呈现先升高后降低的趋势,并在约1 000 m高度处达到最大值。受臭氧前体物由近地面向高空逐渐输送、以及NO向上传输过程中逐渐消耗的影响,臭氧污染日变化曲线出现最大、最小值的时间随高度的升高逐渐推迟;在1 500 m以上的高空,臭氧日变化曲线出现双峰分布。在臭氧污染时段,在高空也观测到高浓度的臭氧污染带,在1 000 m处的臭氧浓度最大值约为570μg/m^3,污染带厚度可超过1 km,持续时间长达数日,且在夜间不能完全消散。观测时段内总计在23个污染日出现高空与近地面臭氧污染的混合,加重了近地面的臭氧污染程度。

Differential absorption lidar combined with near-surface ozone monitoring were used to detect the vertical distribution of ozone in Tianjin from Jun.23 to Sep.28,2018.The monitoring results indicated that the ozone concentration at 300 m above ground showed the same variation tendency as the monitoring values obtained near the ground.In the boundary layer of about 300 m to 1 000 m,the ozone concentration increased with height,but it then decreased at higher altitude.The maximum concentration occurred at approximately 1 000 m above ground.The times when the maximum and minimum concentrations occurred in the diurnal variation curve of ozone were delayed with increasing altitude.This phenomenon was influenced by the gradual transmission process of ozone precursors from the near-surface level to the upper air and the wastage of nitrogen oxide attributable to its oxidation reaction during the transmission process.Above 1 500 m,the diurnal variation curve of ozone showed a double-peak distribution.During the episodes of ozone pollution,the pollution zone with high ozone concentration could be detected frequently in the upper air.The ozone concentration at 1 000 m could reach about 570μg/m^3,and the thickness of the pollution zone could be greater than 1 km.The ozone at high altitude could last for days and sometimes did not dissipate completely at night.In this research,a mixing phenomenon of ozone pollution between high altitude and the near-surface level,which increased the degree of ozone contamination at the near-surface level,was identified 23 times during the ozone pollution days.