京津冀及周边“2+26”城市秋冬季大气重污染气象条件及其气候特征研究

Study on meteorological conditions for heavy air pollution and its climatic characteristics in “2+26” cities around Beijing-Tianjin-Hebei region in autumn and winter

基于1961-2017年的地面常规气象观测资料以及ERA-Interim再分析资料等数据,采用大气自净能力指数(ASI)建立了重污染气象条件等级判别方法。通过对京津冀及周边“2+26”城市秋冬季大气重污染气象条件的长年代变化特征及其成因的分析,得出以下结论:从大气重污染气象条件多年平均水平来看,山西晋城从发生频次到极端性均为最高,北京、河北廊坊和河南郑州多发,河北保定、石家庄和衡水极端性较高。自1961年以来,虽然京津冀及周边“2+26”城市秋冬季大气重污染气象条件在历史上均有发生,但发生次数在2010年后显著增加,这是导致大气重污染频发的重要因素之一。相比2013—2016年,2017年秋冬季京津冀及周边“2+26”城市大气对污染物的清除能力相对较好,虽然北京不利于污染物扩散的气象条件仍然多发,但极端性明显降低。20世纪80年代和2010年以来京津冀及周边地区大气重污染气象条件发生频次均较多,这受到了气候变化背景下冷空气强度和大气滞留条件变化的明显影响,同时也在一定程度上受到了城市化的影响。

Based on surface observation meteorological data during 1961-2017 and ERA-interim reanalysis data, an evaluation method of different meteorological conditions for heavy air pollution (MCHAP) was set up by using atmospheric self-cleaning ability index (ASI). Through analyzing the historical variation characteristics of MCHAP of Beijing-Tianjin-Hebei region in autumn and winter, the results were as follows. During 1961-2017, the frequency and extremity of MCHAP in Jincheng of Shanxi province ranked the first. MCHAP occurred more frequently in Beijing, Langfang of Hebei province and Zhengzhou of Henan province and more extremely in Baoding, Shijiazhuang and Hengshui of Hebei province. MCHAP had occurred in “2+26” cities around Beijing- Tianjin -Hebei region in history since 1961, but which were more common in recent years and caused much more sever air pollution events. During the period of 2013-2017, MCHAP occurred the least frequently in 2017 in “2+26” cities around Beijing-Tianjin-Hebei region except Beijing. However the extremity of MCHAP in 2017 receded a lot in Beijing. Both in the 1980s and the period of 2010-2017, MCHAP in the Beijing-Tianjin-Hebei and its surrounding areas took place the most frequently, which was affected by both the cold air intensity and the change of large-scale air stagnation condition. To some extent, the development of urbanization also plays a role in the decadal change of MCHAP.