沈阳地区臭氧污染日时空变化特征及天气分型研究

利用2013—2019年沈阳地区11个国控监测站近地层臭氧(O_3)浓度监测数据和地面气象观测资料,分析了沈阳地区O_3污染日的O_3浓度时空分布规律,并对造成O_3污染日的天气系统进行了主观分型。结果表明:自2013年以来,以O_3为首要污染物的天数逐年增加,2017年达到研究期内的最高值,但2018—2019年略有下降。O_3浓度的日变化趋势呈现明显的单峰形,O_3-1 h在10:00—20:00明显高于其他时间段,最大浓度值出现在15:00,而在01:00—07:00则相对较低。从季节变化上看,沈阳地区O_3污染主要发生在6—7月,两个月的O_3污染日之和占全年O_3总污染日的比例高达51%。从O_3浓度空间分布上看,沈阳地区三环外监测站测得的O_3浓度明显高于三环内监测站,高浓度区域主要集中在东部和东北部,城市中心存在明显的低浓度区,南部和北部差别不大,但也明显高于城市中心。造成沈阳地区O_3污染的主要天气类型有4种:暖脊型、均压场型、高空槽型和副热带高压型。其中:暖脊型出现的频次最高,占总样本的49.1%;副热带高压型出现的次数最少,占总样本的7.7%。

Study on Spatial and Temporal Variation Characteristics of Ozone Pollution and Weather Classification in Shenyang

Based on the monitoring data of near surface O₃ concentration and surface meteorological observation data of 11 national control points in Shenyang from 2013 to 2019, the temporal and spatial distribution of O₃ pollution daily concentration in Shenyang was analyzed, and the weather system causing O₃ pollution day was classified subjectively. The results showed that since 2013, the number of days with O₃ as the primary pollutant had increased year by year, reaching a high value in 2017, but slightly decreased from 2018 to 2019. The diurnal variation of O₃ showed a single peak. The concentration of O₃ in 10:00-20:00 was significantly higher than that in other time periods. The maximum concentration appeared at 15:00, while the concentration from 01:00 to 07:00 was relatively low. In terms of seasonal variation, O₃ pollution mainly occurred from June to July in Shenyang, and the daily proportion of O₃ pollution was as high as 51%. From the spatial distribution of O₃ concentration, the O₃ concentration of monitoring points outside the third ring road was significantly higher than that inside the third ring road, and the high concentration was mainly concentrated in the east and northeast, and there were obvious low concentration areas in the city center. There was little difference between the southern and northern points, but it was also significantly higher than that of the city center. There were four main weather types causing O₃ pollution in Shenyang:warm ridge type, mean pressure field type, high trough type and subtropical high type. Among them, the warm ridge type had the highest frequency, accounting for 49.1% of the total samples, and the subtropical high type had the least frequency, accounting for 7.7% of the total samples.