杭州市近地面大气臭氧浓度变化特征分析

Characteristics of surface ozone concentration in urban site of Hangzhou

利用2012~2016年杭州市近地面臭氧(O_3)的连续观测资料以及气象数据,分析了杭州市近地面O_3浓度的变化特征及其与气象要素的关系.结果表明,近年来杭州市O_3年平均浓度较10年前升高10μg/m^3左右,光化学污染形势日趋严重.O_3浓度冬季较低,其余季节均较高,日平均浓度大于100pg/m^3主要分布在4~10月.O_3浓度日变化呈单峰型分布,5:00~7:00出现最低值,14:00出现峰值,超标时段主要出现在11:00~18:00.O_3浓度变化与紫外辐射、温度呈正相关关系,与相对湿度呈负相关关系.紫外辐射大于0.02MJ/m^2、气温高于20℃、相对湿度低于70%时,O_3浓度会出现超标情况.风向风速对O_3浓度有一定影响,当风向为北风或偏北风时,O_3浓度较低;当风向为东风或偏东风时,O_3浓度较高,说明影响杭州O_3浓度升高的污染源也主要来自东部,南部和北部地区较少.

The characteristics of surface ozone concentration and its relationship with meteorology were analyzed bycontinuous observation from2012to2016in urban site of Hangzhou.The annual averaged concentration of ozone inHangzhou increased about10μg/m3over the past ten years.The situation of photochemical pollution became worse.Theseasonal variation of ozone concentration was lower in winter and higher in spring,summer and autumn.The dailyaveraged ozone concentration over100μg/m3was mainly scattered from April to October.The daily variation of ozoneconcentration showed unimodal distribution,with a minimum value at05:00~07:00and a maximum value at14:00.Thehourly averaged ozone concentration over standard was mainly appeared at11:00~18:00.The ozone concentration had apositive correlation with ultraviolet radiation and temperature,and a negative correlation with relative humidity.Theozone concentration was in excessive condition while the ultraviolet radiation was higher than0.02MJ/m2,the temperaturewas higher than20℃and the relative humidity was lower than70%.The ozone concentration was influenced by winddirection and wind speed to some extent.The lower ozone concentration was found under north or northerly wind whilehigher ozone concentration was observed under east or easterly wind.The pollution sources which elevated ozoneconcentration came mainly from the east regions of Hangzhou,and less from the south and north regions.