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马丽云, 陈平, 胡景高, 等. 2024. 北疆冬季持续性极端低温事件延伸期的环流异常特征[J]. 大气科学, 48(X): 1−17. doi: 10.3878/j.issn.1006-9895.2212.22032
引用本文: 马丽云, 陈平, 胡景高, 等. 2024. 北疆冬季持续性极端低温事件延伸期的环流异常特征[J]. 大气科学, 48(X): 1−17. doi: 10.3878/j.issn.1006-9895.2212.22032
MA Liyun, CHEN Ping, HU Jinggao, et al. 2024. Characteristics of Circulation Anomalies in Extended Range of the Persistent Extreme Cold Events in Northern Xinjiang during Winter [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(X): 1−17. doi: 10.3878/j.issn.1006-9895.2212.22032
Citation: MA Liyun, CHEN Ping, HU Jinggao, et al. 2024. Characteristics of Circulation Anomalies in Extended Range of the Persistent Extreme Cold Events in Northern Xinjiang during Winter [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(X): 1−17. doi: 10.3878/j.issn.1006-9895.2212.22032

北疆冬季持续性极端低温事件延伸期的环流异常特征

Characteristics of Circulation Anomalies in Extended Range of the Persistent Extreme Cold Events in Northern Xinjiang during Winter

  • 摘要: 本文利用1951~2019年国家气象信息中心逐日站点数据和NCEP/NCAR再分析资料,分析了冬季北疆(新疆北部)持续性极端低温事件(PECE)频次的时空分布特征,并探讨了平流层与对流层在事件发生发展过程中的作用。分析表明:年代际尺度上,北疆PECE在20世纪60年代发生频次最多,此后逐渐减少,表明北疆区域发生该事件的概率在降低。空间分布上,无论是极端低温频次还是冷空气强度,极值中心皆在额尔齐斯河流域一线。北疆PECE发展过程中,平流层和对流层环流皆发生了阶段性的调整。延伸期阶段,距事件爆发前25日时,平流层I区(30°E~120°E)极涡首先开始了由强到弱的转变(欧亚弱极涡型)。行星波向下游频散,东南支波列携带能量影响北疆。至事件爆发前20日,对流层极涡也表现出强度减弱,冷空气分裂南下。此后进入短期阶段,来自北冰洋的冷空气在乌拉尔山高压脊前堆积,使得高压脊加强维持至事件爆发前3日,西伯利亚高压携带冷空气向东南方向扩展,随后对流层大型横槽斜脊引导冷空气南下,地面西伯利亚高压发展强盛向南爆发,3日后冷空气影响北疆地区。

     

    Abstract: In this paper, daily station observational datasets from the National Climate Center and NCEP/NCAR reanalysis datasets during 1951–2019 were used to analyze the temporal and spatial distribution of persistent extremely cold events (PECE) in northern Xinjiang and to discuss the role of the stratosphere and troposphere in the occurrence and development of PECE. The results show that on an interdecadal scale, PECE frequency in northern Xinjiang peaked in the 1960s and gradually decreased since then, indicating that PECE frequency in northern Xinjiang is decreasing. In terms of spatial distribution, the centers of the PECE frequency and cold air intensity were located along the Irtysh River Basin. Stratospheric and tropospheric circulations were adjusted during PECE development. In the extension stage, 25 days before the event outbreak, the polar vortex (30°E–120°E) in the stratosphere began to change from strong to weak (Eurasian weak polar vortex type). Additionally, the planetary wave was dispersed downstream, and the southeastern branch wave train carried energy and affected the northern part of Xinjiang. Furthermore, the tropospheric polar vortex showed signs of weakening, with cold air splitting southwards. Subsequently, it entered a temporary stage. Cold air from the Arctic accumulated in front of the high-pressure ridge of the Ural Mountains and was conducive to the strengthening and maintenance of large inclined ridges. Meanwhile, cold air at the surface accumulated in Central Siberia. Finally, accompanied by strongly developed Siberian High, large-tropospheric troughs and inclined ridges led cold air to the south, which affected northern Xinjiang three days later.

     

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