呼包鄂城市群PM2.5质量浓度统计分布特性

Statistical Characteristics of PM2.5 Concentration in Hohhot-Baotou-Ordos Region

呼包鄂(呼和浩特市,包头市,鄂尔多斯市)城市群位于内蒙古自治区中西部,三市有着非常密切的经贸联系以及相似的气候特征.对呼包鄂三市2014年1月-2017年12月间PM2.5日均质量浓度进行统计性分析.采用四种双参数分布,即Log-normal分布,Weibull分布,Birnbaum-Saunders分布,Gamma分布,拟合三市PM2.5日均质量浓度.用极大似然估计和矩估计估计各分布参数,研究最优理论分布.并对三市PM2.5日均质量浓度作比较.估计结果表明无论是以年为单位还是以四年为整体,三市PM2.5日均质量浓度用Log-normal分布模拟最优;PM2.5日均质量浓度由高到低依次为包头市,呼和浩特市,鄂尔多斯市;包头市和呼和浩特市PM2.5日均质量浓度相似度较高.

Hohhot-Baotou-Ordos Region is located in midwest of Inner Mongolia. There is a close relationship in the fields of economy, trade and climate. We analyze the statistical characteristics of the PM2.5 data measured from January 2014 to December 2017. Four two-parameter distributions, i.e., Log-normal distribution, Weibull distribution, BirnbaumSaunders distribution and Gamma distribution, are used to fit PM2.5 concentration of the three cities. The maximum likelihood estimation and moment estimation are used to calculate the unknown parameters. The research showns that the Log-normal distribution is the optimal model to simulate PM2.5 under the maximum likelihood estimation, whether in years or in four years as a whole. The order from high to low of PM2.5 is Baotou, Hohhot and Ordos. the Pearson correlation coefficient betweem Baotou and Hohhot are of high similarity.