Key Role of Arctic Sea‐Ice in Subseasonal Reversal of Early and Late Winter PM<sub>2.5</sub> Concentration Anomalies Over the North China Plain
Xiadong An, Wen Chen, Tianjiao Ma, Hasi Aru, Qingyu Cai, Li Chun, Lifang Sheng
Abstract
Abstract The PM 2.5 (fine particulate matter with diameter ≤2.5 μm) concentration anomalies over the North China Plain (NCP) in early and late winter sometimes show a subseasonal reversal, which brings a great challenge for precise control of air pollution, and mechanisms are not well understood. This paper reveals the key role of the Barents Sea sea‐ice in this reversal. In early winter, a negative Scandinavian‐like pattern causes an anticyclonic anomaly over Northeast Asia and thus leads to the positive PM 2.5 concentration anomaly over the NCP. In addition, anomalous warm advection associated with the positive North Atlantic Oscillation‐like pattern accelerates winter sea‐ice loss in the Barents Sea, especially in late winter, which increases the surface turbulent heating flux. These heating causes a negative Polar/Eurasian‐like pattern that induces a cyclonic anomaly over Northeast Asia and eventually leads to a negative PM 2.5 concentration anomaly over the NCP in late winter. Vice versa.