宁波臭氧浓度时空变化特征与相关气象因子分析和预报

Spatial-temporal Variation Characteristics of Ozone Concentration and the Analysis and Prediction of Related Meteorological Factors in Ningbo

利用20152018年宁波市O_(3)浓度和气象数据,分析了宁波市O_(3)浓度时空变化特征及三个特征区(市中心、化工区、郊区)O_(3)超标日特点及其天气形势分型,结果表明:宁波市O_(3)浓度分布区域特征明显,总体呈北高南低分布。季节性变化特征为冬季低、春夏季高,45月、79月O_(3)月浓度超过二级标准。三个特征区O_(3)年超标日数均是郊区的>化工区的>市中心的,市中心O_(3)年超标日数为10天左右,化工区为30~40天,郊区为3455天。O_(3)污染出现在211月,O_(3)超标天数和污染程度不成正比,超标天数不多的月份,其污染程度可能相对更严重。日变化趋势比较一致,1 h平均值分别在0607时和1415时达到谷值和峰值。宁波市O_(3)超标日共分为5种天气形势:高压型最多,占26.0%;其次是台风(低压)外围型和均压型,分别占22.8%和21.3%;高压脊型和低压槽型相对较少,低于20.0%。与O_(3)浓度相关性较高的气象要素有14时气温、日最小相对湿度、日照时数、14时风向、0915时是否下雨。根据该5项因子与O_(3)超标率的相关性,确定O_(3)污染气象条件总指数(OPMI),再与前一日O_(3)最大8 h浓度建立线性回归预测方程。利用2019年O_(3)相关实况数据对方程预报结果进行检验,预报和实况相关系数达0.780,说明方程对O_(3)浓度有较好的预测效果。

The spatial and temporal distribution of ozone concentration in Ningbo is statistically analyzed and the characteristics and synoptic situations of days of ozone(O_(3))exceeding the standard value are studied by using the O_(3) and meteorological data observed in Ningbo from 2015 to 2018.The results show that the distribution of O_(3) concentration in Ningbo has obvious regional characteristics and the overall distribution is high in the north and low in the south of Niningbo.The seasonal variations of O_(3) are low in winter and high in spring and summer.The monthly O_(3) concentrations exceed the Secondary Standard from April to May and also from July to September.The number of days with O_(3) exceeding the standard in three seasonal characteristic areas is:suburban areas>chemical industrial areas>downtown areas.There are about 10 days with O_(3) exceeding the standard in downtown,3040 days in chemical industrial area and 3455 days in the suburbs.Ozone pollution occurs from February to November in a year,and the number of O_(3) days exceeding the standard is not proportional to the pollution degree.In the months with a few days exceeding the standard,the O_(3) pollution may be more serious.The diurnal variation trend of O_(3) is consistent.The 1h average O_(3) value reaches its minimum and maximum at 0607 and 1415,respectively.There are five types of synoptic conditions that can lead the ozone concentrations to exceed the standard,including high-pressure(26.0%),typhoon(low-pressure)periphery(22.8%),equalizing field(21.3%),high-pressure ridge and low-pressure trough are below 20%.The meteorological elements with high correlation with O_(3) concentration include temperature at 14:00,daily minimum relative humidity,sunshine duration,wind direction at 14:00,and whether it rains from 0915.According to the correlation between the five elements and the over-standard rate,the total index of O_(3) pollution meteorological conditions(OPMI)is determined,and then the linear regression prediction equation is established with the OPMI and the maximum 8 h concentration of O_(3) in the previous day.The prediction results of the equation are tested by using the O_(3) observation data in 2019,and the correlation coefficient between prediction and observation is 0.780,which indicates that the equation has a good prediction effect on O_(3) concentration.