基于无人机观测的不同污染天气O_(3)垂直分布特征

Vertical distribution characteristics of O_(3)under diverse polluted weather based on unmanned aerial vehicle observations

为了解不同污染天气下近地面O_(3)垂直分布及演变特征,利用无人机及机载环境气象设备于2022年8~9月在山西省大同(清洁天)、太原(污染天)、临汾(污染天转清洁天)进行了33次外场观测,获得了近地面500m内每日06:00、10:00、15:00和19:00O_(3)、总挥发性有机物(TVOCs)、二氧化氮(NO2)和气温、湿度垂直分布.结果表明:O_(3)浓度随高度增加而上升,但15:00主要表现为下降(太原、临汾)或均匀分布(大同);NO2和TVOCs浓度则均为随高度增加而下降.大同O_(3)垂直分布日变化为随高度垂直递增—均匀分布(或递增减弱)—垂直递增,太原、临汾主要为垂直递增—垂直递减—垂直递增.受不同高度区域输送影响,光化学反应期间(10:00~15:00)垂直方向O_(3)日变幅形成2种类型分别是高空—接地层O_(3)浓度同步增高型和接地层增高—高空基本稳定型.白天垂直扩散条件越好,午后污染峰值期间O_(3)垂直递减越显著.受夜间逆温层影响,边界层中上层储存的O_(3)会持续影响第二日O_(3)垂直分布及地面浓度.各观测城市近地面均为VOCs控制区,随着高度的上升逐渐转为共同控制区及NO_(x)控制区,观测期间O_(3)浓度越高VOCs控制区的高度也越高.

In order to understand the vertical distribution and evolution characteristics of near-surface O_(3)under diverse polluted weather,33 in-situ observation experiments were conducted by the unmanned aerial vehicle(UAV)and airborne environmental meteorological equipment in Datong(clean days),Taiyuan(polluted days),and Linfen(polluted days to clean days)of Shanxi Province from August to September 2022,and the daily O_(3),Total Volatile Organic Compounds(TVOCs),Nitrogen Dioxide(NO_(2))and vertical distribution of temperature and humidity under 500m of the near-surface at 06:00,10:00,15:00,and 19:00 were obtained.The results show that the O_(3)concentration mainly increased with height,but decreased(Taiyuan and Linfen)or kept uniform distribution(Datong).The mass burden of NO_(2)and TVOCs both decrease with height.The daily change of vertical distribution of O_(3in)Datong was vertical increasing-uniformly distributed(or increasing and decreasing)-vertical increasing with height,while Taiyuan and Linfen were mainly vertical increasing-vertical decreasing-vertical increasing.Two types of vertical O_(3)daily variability caused by the regional transport at different heights were formed during the photochemical reaction period(10:00~15:00),namely,the simultaneous increase of O_(3)concentration in the upper air-grounding layer and the increase in the grounding layer-the basic stability in the upper air.The better the vertical diffusion conditions were,the more significant the vertical decrease of O_(3)would be during the pollution peak in the afternoon.Due to the influence of the nighttime inversion layer,the O_(3)stored in the upper layer of the boundary layer will continue to affect the vertical distribution of O_(3)and the ground level concentration on the second day.The near-surface VOCs control zones in each observation city gradually changed to common control zones and NO_(x)control zones with the rise of altitude,and the higher the O_(3)concentration,the higher the altitude of the VOCs control during the observation period.