2014年冬季珠三角区域典型城市PM_(2.5)污染时空关联特征

Investigation of Spatial and Temporal Association of PM_(2.5)Pollution during Winter 2014 in Typical Cities of Pearl River Delta

为探讨冬季珠江三角洲(下称珠三角)区域污染物的空间传输延迟性及其与气象、地理的关联性,利用2014年12月1日—2015年1月9日天气图、珠三角区域4个典型城市——韶关、广州、深圳、香港的地面气象数据及ρ(PM_(2.5)),采用时间序列、相关性分析等方法,分析了2014年冬季各城市大气ρ(PM_(2.5))变化关联特征以及受天气过程的影响.结果表明:在研究时段内,受11次冷空气南下和3次西南暖湿气流控制的典型天气过程影响,4个典型城市的ρ(PM_(2.5))小时均值、日均值的时间序列变化趋势具有一致性,并且4个城市间的ρ(PM_(2.5))相关性均呈现深圳与香港>广州与深圳>韶关与广州的现象.在冷空气南下的典型天气过程中,4个城市ρ(PM_(2.5))小时均值存在显著相关,其中,韶关与广州的相关系数为0.84,广州与深圳的相关系数为0.80,深圳与香港的相关系数为0.92;4个城市间ρ(PM_(2.5))变化存在一定的滞后现象,其中,广州较韶关延迟4 h,深圳较广州延迟3 h,香港较深圳延迟1 h;而在西南暖湿气流控制的典型天气过程中,4个城市间ρ(PM_(2.5))变化的关联特征不明显.研究显示,冬季珠三角区域污染物在典型冷空气南下过程中存在较明显的空间传输延迟特征,并且各典型城市间浓度变化相关性较显著.

This study explored the time-lag in regional transport of pollutants over the Pearl River Delta（ PRD）,and the relationship between the time lags and the surface synoptic processes as well as geographic positions,in order to provide reference for the regional warming forecast and pollution prevention over PRD. Based on weather charts,surface synoptic data and PM_（2.5）concentration data from four cities（ Shaoguan,Guangzhou,Shenzhen and Hong Kong）from 1^st December 2014 to 9^th January 2015,the trend of PM_（2.5）concentration over the aforementioned four cities was analyzed,and the relationship between the surface synoptic processes and PM_（2.5）concentration levels were identified by time series and correlation analysis. The results showed that, due to the influence of synoptic process, including cold airflow moving southward（ 11 episodes） and warm-wet southwest airflow control（ 3 episodes）,the overall trend of PM_（2.5）concentrations for the four cities was consistent in both hourly and daily concentrations.Moreover,the correlation coefficients decreased in the following order： Shenzhen Hong Kong Guangzhou Shenzhen Shaoguan Guangzhou. During the process of cold airflow moving southward,there was noticeable correlation between PM_（2.5）concentrations of the four cities,and the correlation coefficients of the hourly correlation were： 0. 84 between Shaoguan and Guangzhou,0. 80 between Guangzhou and Shenzhen,and 0. 92 between Shenzhen and Hong Kong. There were time lags for the concentrations of those cities：Guangzhou four hours later than Shaoguan,Shenzhen three hours later than Guangzhou,and Hong Kong one hour later than Shenzhen.However,the correlation between the four cities was not significant during the process of warm-wet southwest airflow control process.Overall,the process of cold airflow moving southward considerably affected the relevance of PM_（2.5）pollution during winter in the Pearl River Delta. Therefore,there was an obvious time-lag character of the regional transport of pollutants over the PRD during typical process of cold airflow moving southward,and the relationship between the air pollutant concentration trends of the typical PRD cities was remarkable.