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ISSN 1006-9895

CN 11-1768/O4

乌拉尔阻塞高压的维持发展及其与2020/2021年冬季强寒潮活动的关系
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中国科学院大气物理研究所

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本文由国家自然科学基金重点项目(41730959)、国家重点研发计划课题(2018YFC1505601)和国家自然科学基金面上项目(41975072)资助


The Maintenance and Development of Ural Blocking High and its Relationship with Severe Cold Wave Activities in 2020/2021 Winter
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    摘要:

    2020年岁末至2021年初前后两次强寒潮侵入我国,引起大范围的强烈而持续的降温。本文对于其相应的环流特点及成因进行了分析研究,主要结论是:1)从环流形势看,两次寒潮的发展过程,都是属于“横槽转竖”的类型。但是,自2020年的12月中旬至第二次寒潮结束,乌拉尔地区始终维持着宽广的高压脊(阻高),并未出现阻塞崩溃或不连续后退的现象。这与多数东亚地区寒潮爆发时的环流特点有差别。2)乌拉尔阻塞高压及其脊前北风的加强和维持,使其前侧的斜压性大大加强。下游槽底的等高线日益密集,冷平流也不断发展,增强和向南推进。这些都推动了西伯利亚高压的加强和南扩。3)在两次寒潮过程发生之前,源自0°E附近的低频静止波能量向东传播,有利于乌拉尔高压脊的维持、加强以及其下游低槽发展,为冷空气的向南爆发提供有利条件。

    Abstract:

    Two successive severe cold waves invaded eastern China during the period from the late 2020 to early 2021, leading to extensive, severe and persistent drop in temperature. The paper investigates the features and formation mechanisms of the circulations associated with these two cold waves. The main results are as follows: 1) The circulations of these two cold waves are both be recognized as a kind of “anticlockwise turning of transverse trough”. However, a broad ridge (or blocking high) was maintained over the Ural area from mid-December 2020 till the end of the second cold wave. No breakdown or “discontinuous westward shift” of blocking high was observed, which is different from the common cold waves in eastern Asia. 2) The maintenance and strengthening of northerly wind in front of the Ural high leads to the increase of baroclinicity in situ. In the downstream, the gradient of the geopotential height contour in the south of the transverse trough rapidly increases and the cold temperature advections are consistently enhanced and southward advanced. All of these cause the intensification and southward expansion of the Siberian High. 3) Prior to the occurrence of the two cold waves, the energy of low frequency stationary wave originating from at 0°E (or even to the west) propagates eastward, which favors the maintenance and intensification of the Ural ridge and the development of the trough downstream, providing a favorable condition for the southward outbreak of cold air.

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  • 收稿日期:2021-09-02
  • 最后修改日期:2022-01-14
  • 录用日期:2022-06-20
  • 在线发布日期: 2022-06-20
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