降水量与城市大气环境关系——以113个环保重点城市为例

为研究降水量与大气污染物之间的关系,依据2017年全国113个环保重点城市大气质量数据,得出城市聚类空间分布规律及两者之间线性拟合方程。基于南北降水量分布特性与城市空气污染指数,采用模糊聚类法对具有不同亲疏程度的城市进行类别划分,运用Spearman相关性与拟合方程对大气污染特征值与降水量进行分析。结果表明：随着聚类种数增多,城市聚集在空间分布上由“环环相套”发展为“依流域分布”,降水量与大气污染物浓度呈现负向关联性,晋冀鲁豫陕省份污染最严重。采用Kolmogorov-Smirnov检验法,得出NO₂、O₃、PM_2.5总体分布符合正态分布,SO₂、PM₁₀、CO既不符合正态分布,也不符合均匀、指数分布,它们与降水量的相关系数为：-0.316、-0.238、-0.332、-0.617、-0.574、-0.695;线性拟合方程系数处于 -0.031, -0.008] 之间,降水量与大气污染物浓度之间负相关性明显。研究结果有助于了解和认识降水量对城市大气环境变化的影响。

Study on the relationship between precipitation and urban atmospheric environment: Cases of 113 key environmental protection cities

In order to study the relationship between precipitation and atmospheric pollutants, according to the air quality data of 113 key environmental protection cities in China in 2017, the spatial distribution law of urban clusters and the linear fitting equation between them are obtained. Based on the distribution characteristics of precipitation in the north and south and the urban air pollution index, the fuzzy clustering method was used to classify cities with different degrees of affinity. The Spearman correlation and fitting regression method were used to analyze the air pollution characteristic value and precipitation. The results show that when the key environmental protection cities are clustered into five categories, the spatial distribution of "rings and loops" is presented. The innermost ring basically covers five provinces of Hebei, Henan, Shandong, Shanxi and Shaanxi. The rest of the city is distributed between the second and third rings, and the urban air quality gradually increases from the inside to the outside. As the number of clusters increases, the urban agglomeration pattern changes, and the spatial distribution develops into "distribution according to the basin", but the "circle" city does not change much. In this clustering situation, the impact of the amount of precipitation on the atmospheric quality environment of environmentally friendly cities can be clearly reflected. The precipitation is negatively correlated with the concentration of atmospheric pollutants, and the environment in these five provinces is seriously polluted. Using Kolmogorov-Smirnov test method, it is calculated that the overall distribution of NO₂, O₃ and PM_2.5 conforms to the normal distribution, and that of SO₂, PM₁₀ and CO does not conform to the normal distribution, nor does it conform to the uniform and exponential distribution. The correlation coefficients of NO₂, O₃, PM_2.5, SO₂, PM₁₀ and CO with precipitation are -0.316, -0.238, -0.332, -0.617, -0.574 and -0.695, respectively. O₃ is in weak correlation; NO₂ and PM_2.5 are in moderate correlation; SO₂, PM₁₀ and CO are in strong correlation. The coefficient of linear regression equation is between -0.031 and -0.008, and the negative correlation between precipitation and atmospheric pollutant concentration is obvious. The research results will help to understand the impact of precipitation on urban atmospheric environment changes, and provide the necessary theoretical support for the sustainable development of urban construction.