气象条件对荆门市PM_(2.5)浓度的影响的非参数分析

Nonparametric Analysis of the Influence of Meteorological Conditions on PM_(2.5)Concentration in Jingmen City

为了分析气象条件对荆门地区PM_(2.5)浓度的影响,为大气污染防治提供决策依据,分月、分季节分析了2015年1月~2017年11月荆门地区PM_(2.5)浓度的分布及变化特征,同时采用非参数方法(Spearman秩相关)分析了各气象要素与PM_(2.5)浓度的相关性,通过散点图分析和重污染案例分析等方法,总结归纳了气象条件对荆门地区PM_(2.5)浓度的影响。结果表明:(1)荆门地区细颗粒物污染冬强夏弱,1月份污染最严重,2015至2017年空气污染呈逐年递减趋势。(2)全年PM_(2.5)的日均浓度与各气象要素的Spearman秩相关性均在0.01水平上均呈显著相关。(3)重污染过程中,气压的变化与PM_(2.5)浓度的相关性最大,其次是地面风向风速、日照时数和降水量,此外相对湿度偏高时,污染较重。(4)荆门地区的重污染天气多发生在偏北风环境下,外源输送型污染较本地积累型污染要更为严重,冬季冷锋系统过境、有云层覆盖并且出现弱降水时,易出现重污染。综合来看,气象条件对荆门地区PM_(2.5)浓度的影响较大,尤其是在冬季有冷空气带动污染气团南下的外源输送型污染过程中,气象条件的影响更为显著。该研究成果在国内首次阐述了荆门地区气象条件对PM_(2.5)浓度的影响,为江汉平原北部地区的大气污染防治工作提供了技术支撑,具有指导意义。

In order to analyze the impact of meteorological conditions on PM_(2.5)concentration in Jingmen area and provide decision-making basis for air pollution prevention and control,this paper analyzed the distribution and variation characteristics of PM2.5 concentration in Jingmen area from January 2015 to November 2017 by month and season,and analyzed the correlation betweenmeteorological elements and PM_(2.5)concentration by non-parametric method(Spearman rank correlation).Through scatter diagram analysis and heavy pollution case analysis,the influence of meteorological conditions on the concentration of PM_(2.5)in Jingmen area was summarized.The results showed that:(1)the fine particulate matter pollution in Jingmen area was strong in winter and weak in summer,and the pollution was the most serious in January.From 2015 to 2017,the air pollution showed a decreasing trend year by year.(2)The Spearman rank correlation between the annual average daily concentration of PM_(2.5)and meteorological elements was significant at the level of 0.01.(3)In the process of heavy pollution,the change of atmospheric pressure has the greatest correlation with the concentration of PM2.5,followed by the surface wind direction and speed,sunshine hours and precipitation.In addition,when the relative humidity is high,the pollution is heavier.(4)The heavy pollution weather in Jingmen area mostly occurs in the northerly wind environment,and the external transportation pollution is more serious than the local accumulation pollution.Heavy pollution is easy to occur in winter when the cold front system passes through,there is cloud cover and there is weak precipitation.In general,meteorological conditions have a great impact on the concentration of PM_(2.5)in Jingmen area,especially in the process of exogenous transportation pollution driven by cold air mass to the south in winter.This research achievement expounded the influence of meteorological conditions in Jingmen area on the concentration of PM_(2.5)for the first time in China,and provides technical support and guiding significance for the prevention and control of air pollution in the northern Jianghan Plain.