1971-2015年乌兰察布市霾日数时空变化规律及其影响因素

研究乌兰察布地区霾日数的时空分布及其影响因素，对乌兰察布市（乌市）及其上下游地区雾霾形成机理和跨境输送机制的研究提供理论参考。采用乌兰察布市（乌市）1971-2015年11个台站气象数据资料，结合2015年环境污染数据资料，分析乌市长时间序列霾日数时空分布、突变情况、周期尺度变化和形成因素。结果表明，乌市霾日数在长时间序列中呈“减小-消失-增加”的U型变化趋势，主要集中在1971-1981年和2014-2015年2个时间段，1971年发生了显著突变。在空间上主要集中在东南、西南和中部，其中兴和县霾日数远高于其他区县。霾日数的3个尺度周期强度都有减弱趋势，以3~6 a为主的小尺度周期自1982年消失后，于2014年重新出现。霾日数季节分布由春季转变为秋、冬季，这是由于雾霾成因发生了变化，霾的成因从以沙尘天气为主的自然源转变为以PM_2.5等空气污染为主的人为排放源。

Spatiotemporal Variation of Haze Days and the Influencing Factors in Ulanqab,Inner Mongolia from 1971 to 2015

The objectives of this study were to investigate the spatiotemporal distribution of haze days and the influencing factors,and to provide theoretical reference for the study of the haze formation mechanism and cross-border transport mechanism in Ulanqab and its upstream and downstream areas.Using meteorological data from 11 stations in Ulanqab from 1971-2015,combined with environmental pollution data from 2015,we analyzed the spatiotemporal and distribution of haze days in time series,abrupt situations,periodic scale changes and formation factors.The results showed that the number of haze days in Ulanqab showed a U-shaped trend of “decreasing-disappearing-increasing” in the long time series,mainly concentrated in the time periods of 1971-1981 and 2014-2015,with a significantly sudden change in 1971.Spatially,the haze days were mainly concentrated in the southeast,southwest and central regions,with Xinghe County having a much higher number of haze days than other counties.The intensity of all three scale cycles of haze days tended to weaken,and the small-scale cycle dominated by 3-6 years reappeared in 2014 after disappearing since 1982.The seasonal distribution of haze days shifted from spring to autumn and winter,which was due to a change in the causes of haze from natural sources,mainly dusty weather,to anthropogenic emission sources,mainly PM_2.5 and other air pollutions.