研究报告
汪海恒,沈傲,许亦非,黎煜满,刘一鸣,卢骁,樊琦.粤北地区一次臭氧污染过程分析及数值模拟[J].环境科学学报,2022,42(10):49-61
粤北地区一次臭氧污染过程分析及数值模拟
- Analysis and numerical simulation of an ozone pollution process in northern Guangdong province
- 基金项目：广东省重点领域研发计划（No.2020B1111360003）；广东省科技计划项目（科技创新平台类）（No.2019B121201002）
- 作者
- 单位
- 汪海恒
- 中山大学大气科学学院，广东省气候变化与自然灾害重点实验室，广州 510275;广东省韶关市气象局，韶关 512028
- 沈傲
- 中山大学大气科学学院，广东省气候变化与自然灾害重点实验室，广州 510275;南方海洋科学与工程广东省实验室（珠海），珠海 510405
- 许亦非
- 中山大学大气科学学院，广东省气候变化与自然灾害重点实验室，广州 510275;南方海洋科学与工程广东省实验室（珠海），珠海 510405
- 黎煜满
- 中山大学大气科学学院，广东省气候变化与自然灾害重点实验室，广州 510275;南方海洋科学与工程广东省实验室（珠海），珠海 510405
- 刘一鸣
- 中山大学大气科学学院，广东省气候变化与自然灾害重点实验室，广州 510275
- 卢骁
- 中山大学大气科学学院，广东省气候变化与自然灾害重点实验室，广州 510275
- 樊琦
- 中山大学大气科学学院，广东省气候变化与自然灾害重点实验室，广州 510275;南方海洋科学与工程广东省实验室（珠海），珠海 510405
- 摘要：2020年7月1日，粤北地区出现了一次O3污染过程，其中韶关市录得全省最高值162 μg·m-3.本文利用常规观测资料以及再分析资料对影响此次韶关地区O3污染过程的主要气象场特征进行分析，结果表明：6月28日—7月2日天气形势总体处于静稳状态，地面受到均压场控制，同时副热带高压较强，脊线位于韶关上空，导致中高层有下沉气流，抑制了垂直方向污染物的扩散.6月28—30日（污染积累阶段），风速较大，韶关在外来输送和污染扩散条件的共同作用下，O3浓度上升但未超标.7月1日（污染持续阶段），韶关和清远两地风速减小，污染扩散条件不利；同时气温有所上升，光化学反应作用增强，有利于O3浓度攀升；同时广州和佛山两地的风向从偏南风转为偏北风，韶关市维持偏南风，主导风向的差异是全省只有韶关O3超标的主要原因.7月2日（污染消散阶段），O3外来传输及本地生成作用减弱，全省O3浓度下降.进一步利用HYSPLIT后向轨迹以及WRF-CMAQ空气质量模式对3个阶段臭氧浓度变化的原因进行定量分析，结果表明：在积累阶段污染气团主要来源于广州、佛山和清远，外来输送作用明显；而在持续阶段3地O3浓度低，O3外来输送作用减弱；WRF-CMAQ模型定量过程诊断分析得出污染积累和持续阶段广州的水平平流输送项均为负贡献，分别达30%和18%，输出作用显著，但污染积累阶段较大的风速使得O3在韶关地区无法堆积，韶关地区的水平输送正贡献项占比仅为12%；而在持续阶段，风速减小有利于污染物堆积，此阶段00：00—08：00时水平平流贡献项占比达59%，另外10：00—16：00本地气相化学过程的贡献项占比达56%.因此外地输送堆积以及本地气相化学生成共同造成了此次韶关地区的O3污染过程.
- Abstract：On July 1， 2020， an O3 pollution process occurred in northern Guangdong province， and the highest value of 162 μg·m-3 was recorded in Shaoguan city. In this paper， conventional observation data and reanalysis data were used to analyze the main meteorological field characteristics that affect this O3 pollution process， and the results showed that： From June 28 to July 2， the weather situation was generally stable， and the ground was controlled by the mean pressure field. Meanwhile， the subtropical high was strong， and the ridge line was located over Shaoguan， leading to the downdraft at the middle and upper levels， which inhibited the diffusion of pollutants in the vertical direction. From June 28 to 30 （pollution accumulation stage）， the wind speed was relatively high. Under the combined action of external transport and pollution diffusion conditions in Shaoguan， O3 concentration increased but did not exceed the standard. On July 1 （pollution persistent stage）， the wind speed in Shaoguan and Qingyuan decreased， and the pollution diffusion conditions were not favorable； at the same time， the temperature increased and the photochemical reaction enhanced， which was conducive to the increase of O3 concentration； At the same time， the wind direction in Guangzhou and Foshan cities changed from southerly to northerly， while shaoguan maintained southerly， therefore the difference in dominant wind direction was the main reason that only the O3 concentrations in Shaoguan city exceeded the standard in Guangdong province. On July 2 （pollution dissipation stage）， the effect of O3 external transmission and local generation weakened， and O3 concentration decreased in the whole province. Moreover， the HYSPLIT backward trajectory and WRF-CMAQ air quality model were used to quantitatively analyze the causes of ozone concentration changes in three stages， and the results showed that： In the accumulation stage， the air mass mainly came from Guangzhou， Foshan and Qingyuan， and the external transport effect was obvious； however， the concentrations of O3 in these three places were low in the duration stage， and the external transport effects of O3 were weakened； The quantitative process diagnostic analysis of WRF-CMAQ model showed that the horizontal advection transport terms in Guangzhou were negative contributions of 30% and 18%， respectively in the pollution accumulation and duration stages， indicating a significant output effect. However， the high wind speed in the pollution accumulation stage made O3 unable to accumulate in Shaoguan， and the positive contribution terms of horizontal transport in Shaoguan accounted for only 12%； In the sustained stage， the reduced wind speed was conducive to the accumulation of pollutants. In this stage， the contribution of horizontal advection from 00：00 to 08：00 accounted for 59%， and the contribution of local gas phase chemical process from 10 to 16 accounted for 56%. Therefore， the field transport accumulation and the local gas phase chemical generation jointly caused the O3 pollution process in Shaoguan area.
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