1981—2018年中国东北地区秋冬季霾日变化及其与北极海冰的关系

利用中国东北地区1981—2018年166个地面气象观测站资料, 定义了中国东北地区秋冬季霾日指数, 分析了年际尺度上该地区霾日数与同期大气环流异常的内在关系。结果表明: 中国东北地区秋冬季霾日指数存在显著的年际变化特征, 欧亚—太平洋遥相关型(Eurasia-Pacific Teleconnection Pattern, EUP)负位相、东亚大槽偏弱等大气环流异常配置导致中国东北地区秋冬季霾的发生频次增加。巴伦支海与喀拉海北部海域是影响中国东北地区秋冬季霾日年际变化的海冰关键区, 该区域海冰面积与霾日数呈显著负相关, 北极海冰通过改变大气环流间接影响中国东北地区秋冬季霾日发生频次, 当北极海冰异常偏少时, 东亚冬季风偏弱, 近地面风速偏低, 环境湿度偏高, 中国东北地区受东北亚异常反气旋西侧的异常偏南风控制, 且受“EUP”负位相模态影响, 东亚大槽减弱, 有利于大气污染物和水汽向中国东北地区输送, 该地区秋冬季霾的发生频次增加。

Variation of haze days in Northeast China in autumn and winter and its relationship with Arctic sea ice from 1981 to 2018

Using observational data at 166 meteorological stations in Northeast China from 1981 to 2018, we defined a haze-day index in autumn and winter in Northeast China and analyzed the internal relationship between the number of haze days and the atmospheric circulation anomalies. The results indicated that the haze-day index in autumn and winter in Northeast China exhibits a significant interannual variation.The configuration of atmospheric circulation anomalies such as the negative phase of the Eurasia-Pacific Teleconnection Pattern (EUP) and the weak East Asian trough leads to the increase in the occurrence frequency of haze events during autumn and winter in Northeast China. The Barents Sea and the northern Kara Sea are key areas of sea ice that affect the interannual variation of haze days in autumn and winter over Northeast China. The area of sea ice in this region has a significantly negative correlation with the number of haze days. The atmospheric circulation indirectly affects the occurrence frequency of haze events in autumn and winter in Northeast China. When the area of Arctic sea ice is anomalously low, East Asian winter monsoon is relatively weak, near-surface wind speed is low, and ambient humidity is high. Meanwhile, Northeast China is controlled by the abnormal southerly winds on the western side of the Northeast Asian abnormal anticyclone and is influenced by the negative phase mode of EUP, and the large trough in East Asia is weakened, which favors the transport of air pollutants and water vapor to Northeast China, increasing the frequency of haze events in autumn and winter in this region.