Abstract:  Based on the meteorological observation data of air pollutant mass concentration and meteorological elements in Hohhot, and NCEP FNL reanalysis data with 1°× 1° resolution from 2015 to 2019, the air quality and meteorological conditions, and the characteristics of atmospheric boundary layer in winter in recent 5 years were analyzed, then the change characteristics of meteorological conditions leading Hohhot’s frequent air pollution in winter in 2019 were summarized. The results are as follows: (1) It was prone to occur pollution during winter in Hohhot, the main pollutant was PM2.5. The pollutants were difficult to diffuse, the pollution lasted for a long time, and pollution days and percentage of heavy pollution days increased significantly, which were exhibited in winter of 2019. (2) The average wind speed was relatively smaller, the small wind days were relatively more, the frequency of south wind increased, the relative humidity was higher, the mixed layer height was lower, the ventilation coefficient was weaker and the temperature inversion days were more in Hohhot in winter of 2019.

Key words: Key words: frequent air pollution,  meteorological conditions,  the characteristics of atmospheric boundary layer,  air quality index (AQI)

摘要： 利用2015—2019年呼和浩特市大气污染物质量浓度、气象要素观测及NCEP FNL 1°×1°再分析资料，分析近5 a冬季环境空气质量特征及与大气污染扩散紧密相关的气象要素和大气边界层特征，研究2019年冬季呼和浩特市大气污染频发的气象条件变化特征。结果表明：（1）呼和浩特市冬季较易出现污染天气，以PM2.5污染为主，2019年冬季，大气污染呈现出污染物积聚难于扩散、污染长时间持续、污染天数和重污染占比均显著增高等特点。（2）2019年冬季呼和浩特市气象条件呈现出平均风速偏小、小风日数偏多、南风出现频率增多、相对湿度偏高、混合层高度偏低、通风系数较小、逆温日数较多等特征。

关键词: ">大气污染频发；气象条件；边界层特征；空气质量指数（AQI）