上海市PM2.5浓度变化特征及其气象因子分析

对上海市2012-2016年PM_2.5质量浓度、气象因素数据资料进行整理统计，通过定性分析与定量计算相结合的方法，揭示近年来上海市PM_2.5浓度的变化特征及其污染状况；采用相关性分析，从温度、气压、相对湿度、风向、风速和降水量等方面探讨了PM_2.5浓度与气象因素之间的关联性。结果表明：上海市近5 a空气质量主要为优和良，污染天数所占全年比例在减少。PM_2.5浓度呈现出夏季低，冬季高的季节特征，而且8月PM_2.5浓度最低，处于16~36 μg·m^-3；PM_2.5的日变化呈现出双峰双谷结构，浓度峰值出现于8~9时和19~20时，且后者浓度更高。气温、气压、相对湿度的阈值分别出现在9.8℃、1 021.6 hPa、83%，最大PM_2.5在阈值处出现显著变化；最大PM_2.5浓度与累积风速和降水量呈现出对数关系，并且东北风和东南风的累积风速达到350 m·s^-1以上时，PM_2.5浓度基本减少至35 μg·m^-3；降水量越大，PM_2.5浓度越低。

Characteristics of PM2.5 concentration variability and its meteorological factors in Shanghai

This paper systematically analyzes the temporal variability of the mass concentration of PM_2.5 in Shanghai,and discusses the effects of meteorological factors on the concentration of PM_2.5.It reveals the temporal variability of the PM_2.5 concentration and the status of atmospheric pollution in recent years in Shanghai through multi-scale statistics,qualitative analysis and quantitative computation on meteorological data provided by China Air Quality Online Monitoring and Analysis Platform,as well as China Meteorological Administration.The correlation analysis is applied in understanding the relationship between the PM_2.5 concentration and meteorological factors (the temperature,air pressure,the relative humidity,wind direction,wind speed and precipitation) in Shanghai from 2012 to 2016.The results showed that most of the time the air quality in Shanghai has been good or excellent in recent 5 years and the number of days when it was suffered from the pollution has been decreasing.The PM_2.5 concentration displayed a seasonal feature which indicated a lower value in the summer and a higher value in the winter with the lowest value in August of 16~36 μg·m^-3.The daily variation shows a structure of two peaks and two valleys,with the concentration peaks occurred during 8:00 AM to 9:00 AM and 7:00 PM to 8:00 PM higher during the latter period.The thresholds of the temperature,the air pressure and the relative humidity were 9.8℃,1 021.6 hPa and 83% respectively which were normally the inflection points of the PM_2.5 concentration.There was a logarithmic relationship between the maximum PM_2.5 concentration and the accumulated wind speed and precipitation.When the accumulated wind speed of northeaster and southeaster reached 350 m·s^-1,the PM_2.5 concentration was decreased to 35 μg·m^-3.The bigger the precipitation was,the lower the concentration of PM_2.5 became.This paper showed a good correlation between meteorological factors and the concentration of PM_2.5,and its numerical model had a positive effect on the prediction of the concentration of PM_2.5 and the treatment for atmospheric environment.