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Impact of atmospheric quasi-biweekly oscillation on the persistent heavy PM2.5 pollution over Beijing-Tianjin-Hebei region, China during winter
Atmospheric Research ( IF 5.5 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.atmosres.2020.105017 Libo Gao , Tijian Wang , Xuejuan Ren , Bingliang Zhuang , Shu Li , Ruan Yao , Xiu-Qun Yang
Atmospheric Research ( IF 5.5 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.atmosres.2020.105017 Libo Gao , Tijian Wang , Xuejuan Ren , Bingliang Zhuang , Shu Li , Ruan Yao , Xiu-Qun Yang
Abstract In recent years, persistent heavy PM2.5 pollution (PHP) events occurred frequently over the Beijing-Tianjin-Hebei (BTH) region in China, which posed a great threat to human life. This study investigates the evolution of PHP over the BTH region in China and its relation with atmospheric quasi-biweekly oscillation. A significant periodicity of 10–16 days of the PM2.5 concentration over the BTH region is observed in winters of 2013–2017, which notably contributes to the occurrence of PHP. A total of 12 PHP events are identified in the five winters. The life cycle of PM2.5 pollution containing those PHP events is divided into eight phases according to the quasi-biweekly variation of PM2.5 pollution over the BTH region. The phase composites of circulation fields show that the atmospheric quasi-biweekly oscillation provides favorable conditions for the persistence of air pollution over the BTH region in winter. During the PHP events, the quasi-biweekly southerly anomalies prevail persistently over eastern China. The East Asian winter monsoon is weakened and more moisture is transported to the BTH region continuously. The anomalous warming in the lower troposphere indicates a stable stratification on a quasi-biweekly time scale. Moreover, in the mid-troposphere, the variation of East Asian trough's intensity is significantly correlated with PHP over the BTH region. It is suggested that the quasi-biweekly oscillation of East Asian trough can be traced back to a precursor signal over northwestern Eurasia about 11 days earlier, through a southeastward wave train propagation. Thus, the meteorological conditions conducive to PHP over the BTH region can be predicted on the quasi-biweekly time scale.
更新日期：2020-09-01
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