| Based on the daily data of the ambient air quality that comes from 34 ambient air quality monitoring stations and 8 National Meteorological stations in Hangzhou,from 2013 to 2018,this paper systematically analyzes the spatial and temporal distribution characteristics of the ambient air quality index,the state of the ambient air quality,the main components of the major pollutant,the main weather pattern of the severe pollution and serious pollution in Hangzhou,and analyzes the correlation between air quality index and meteorological factors by SPSS 19.0.The results show that:The trend of air quality index of 34 environmental monitoring stations and each region is basically the same day by day.From June 21 to July 24,there are obvious daily low value areas,which is highly consistent with the occurrence time of Meiyu period in Hangzhou.The lowest air quality index appears in July and August,with the lowest season—summer and the highest appears in December and January,which means the highest comes in winter.The air quality index shows a downward trend from 2014 to2018.Those whom of Hangzhou is increasing from southwest to northeast,that is,from Chun'an County to Hangzhou City,Xiaoshan District and Yuhang District.The months with high air quality are from June to August,with which proportion of good air quality has little change in the whole year.Those of light and medium pollution peaked in August,with those in heavy and serious pollution was the highest in January and the next highest in December.The excellent ratio increased year by year from 2014 to 2016,fluctuated slightly from 2017 to 2018,and serious pollution decreased year by year.The air quality of Chun'an county is the best,and Jiande City is the second.Yuhang District is the worst and Xiaoshan district is the second worst.The main components of major pollutants are as list: PM2.5 in November to March,O3 in April to September,with some differences among regions in October,PM2.5 in spring,autumn and winter,and O3 in summer,within the scope of O3,PM10,PM2.5 and NO2.PM2.5 is the main pollutant above the level of severe pollution,and PM2.5 and PM10 are the main pollutants exceeding the standard.Severe and serious pollution mainly affect the weather pattern of high pressure center type and the cold front type.The 3-day sliding average of AQI is negatively correlated with precipitation,temperature,minimum temperature,wind speed,and positively correlated with average air pressure and the sunshine.The three meteorological factors with the closest correlation of air quality index are as list: those of Hangzhou urban area,Yuhang district and Xiaoshan district are maximum wind speed,average relative humidity and precipitation;those of Fuyang district and Lin'an district are average temperature,lowest air temperature and average air pressure;those of Jiande City is minimum temperature,average relative humidity and precipitation;those of Tonglu County is minimum temperature,average air pressure and precipitation;those of Chun'an County is average relative humidity,sunshine and precipitation. |
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