深圳市PM_(2.5)浓度变化及污染输送特征分析

Distribution and Transfer Characteristics of PM_(2.5) in Shenzhen

根据2015年1~12月深圳市11个大气自动监测国控站点PM_(2.5)小时浓度监测数据,结合气象站小时观测数据,采用Correl相关系数法、玫瑰图等分析了深圳市PM_(2.5)浓度的污染分布与输送迁移特征。结果显示:2015年深圳市主导风向为NNE(东北偏北风),风向频率为12.3%,全年PM_(2.5)平均浓度为29.8μg/m3,整体季节平均浓度特征均表现为冬季>秋季>春季>夏季;PM_(2.5)与露点、能见度呈显著负相关,相关系数分别为-0.517与-0.540,与海平面气压、温度呈明显的实相关,相关系数为0.439、-0.411,与风向、风速、相对湿度为微相关;深圳吹海风时,参照年均值标准,PM_(2.5)污染发生概率为22.7%,且发生秋冬季海风型PM_(2.5)污染时PM_(2.5)平均浓度可高达50.6μg/m3。主导风型下的PM_(2.5)污染事件占全年PM_(2.5)污染事件的61.1%,且风速大于3m/s时PM_(2.5)污染发生事件占比仅为6.26%;2015年全年西北陆风、主导风、海风气团输送情景下的PM_(2.5)平均浓度分别为40.1、35.8和26.2μg/m3,冬季时西北陆风输送通道下的PM_(2.5)平均浓度整体上明显高于海风、东北偏北陆风输送通道。

Based on the PM2.5 hourly monitoring data from 11 sites of Shenzhen in 2015, the distribution and transfer characteristic of PM2.5 was analyzed with Correl correlation coefficient method and pollution rose. The results showed： 1） the dominant wind direction of Shenzhen was NNE wind in 2015, and the wind direction frequency of NNE was 12.3%. Meanwhile, the annual average PM2.5 concentration of Shenzhen was 29.8μg / m3, the overall av- erage concentration characteristics of each season were expressed as winter〉 autumn 〉 spring〉 summer. 2） PM2.5 has a significant negative correlation with dew--point temperature and visibility, the correlation coefficients were - 0.517 and --0.540 respectively. Furthermore, the PM2.5 concentration showed obvious correlation with pressure and temperature, the correlation coefficients were 0.439 and -0.411, respectively. There was a weak correlation between PM2.5 and wind direction, wind speed and relative humidity. 3） The probability of PM2.5 pollution with sea--wind type （E,ESE,SE,SSE,S） was 22.7%, and the PM2.5 average concentration of PM2.5 pollution accidents in the autumn and winter was 50.6μg/m3.The proportion of PMz.5 pollution （〉 35μg/m3） happened under the scenes of dominant wind type （N, NNE, NE and ENE） was 61.1%. When the wind speed was greater than 3m/s, the proportion of PM2.5 pollution was only 6.26 %. 4） The average PM2.5 concentrations with NW- type （WNW, NW, NNW）, dominant wind type and sea--wind type were 40.1, 35.8 and 26.2μg/m3. In the winter, the average PM2.5 concentrations with NW-- type was much higher than that of dominant wind and sea-wind type.