2012年1月、2016年1月东亚两次极端严寒事件及其与北极增暖的可能联系
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国家自然科学基金资助项目(41790472;41730959;41475080);国家重点基础研究发展计划(973计划)项目(2015CB453200)


Two extremely cold events in East Asia in January of 2012 and 2016 and their possible associations with Arctic warming
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    摘要:

    自20世纪80年代后期以来,我国频繁出现暖冬,直到2004年以后这种状况出现明显的变化,冷冬出现的频次明显增多了。在全球增暖、北极海冰减少明显的背景下,冬季极端严寒的强度非但没有减弱反而似乎还在增强,造成灾害性的影响也越发引人关注。在上述背景下,2012年1月、2016年1月在东亚发生了两次极端严寒事件。本文的目的就是通过合成和相关分析,研究这两次极端严寒事件演变的主要特征,及其与北极增暖的可能联系。
    这两次极端严寒事件的环流演变截然不同。对于2012年1月的极端严寒事件,海平面气压异常主要呈现由东向西传播,在演变过程中,阿留申区域海平面气压超前西伯利亚高压,因此大气环流的下游效应起主要作用。对于2016年1月的极端严寒事件,冷空气主要由西北向东南传播。两次极端事件的主要降温区域的移动路径截然不同。2012年1月冷空气爆发以后主要在亚洲大陆中、高纬度维持并向西传播,其南传影响亚洲低纬度区域明显弱于2016年的冷事件。而2016年1月的主要降温区以沿东亚向南移动为主,强降温区直接南下至热带区域。
    两次极端严寒事件爆发前期大气环流演变的共同点:中、高纬度区域环流能量交换活跃,表现为中纬度高度脊加强北伸,从而把较低纬度的暖空气输送至北极区域,高纬度区域对流层中层呈现多极结构。这种多极空间结构是亚洲冷空气向南爆发的重要前兆信号。冬季北极阶段性增暖过程首先是中纬度高度脊加强北伸的结果。对影响东亚的极端严寒过程,乌拉尔附近区域的高压脊以及位于北美西部的高压脊加强北上、协同演变是至关重要的。2016年1月东亚极端严寒过程与2015年12月末北极快速增暖没有必然联系。

    Abstract:

    Warm winter prevailed in China from the late 1980s to the beginning 2000,and then cold winter seems to be more frequent.Intensity of winter extremely cold events appears to be further strengthened in the context of global warming and Arctic sea ice decline,its impacts have been concerned by the public and media.In the above context,East Asia suffered extremely cold events during January of 2012 and 2016.Thus the motivation of the present study is to investigate dominant features of the two extremely cold events and their possible linkages with Arctic warm anomalies.Evoluions of atmospheric circulation anomalies associated with the two extremely cold events are quite distinct from each other.For the extremly cold event in January 2012,SLP anomalies display a westward propogation process,during which the Aleutian Low led the Siberian High,indicating that the effect of downstream of atmospheric circulation anomalies plays important roles in resulting in the westward propogation.For another event,cold air mass exhibited a southeastward migration.The routes of the low-temperature area are also distinct for the two events.The former,cold air mass was mainly confined to the mid-and high-latitudes of Eurasia and migrated westward,and its impact on the low-latitudes of Asia was weaker relative to the latter.For the cold event in January 2016,the low-temperature area propaged southward along East Asian coast and affacted the tropic region.Atmospheric circulation anomalies exhibited a common feature prior to the outbreak of both extremely cold events:enhanced height ridges extended northward and transported more warmer air mass from the low-latitudes into the Arctic,and there was a multipole structure in the mid-troposphere of high-latitudes.This multipole sturcture is an important precoursor for outbreak of cold air mass.During wintertime,a rapid warming process in the Arctic can be attributed to enhanced warm ridge and its extension northward.Enhancement and extension northward of warm ridges over the Ural Mountain and West coast of North America and their coordinated evolution are critical for a extremely cold process to affect East Asia.The extremely cold event in East Asia in January 2016 did not exhibit a relation with a rapid Arctic warming process in December 2015.

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  • 收稿日期:2018-07-24
  • 最后修改日期:2018-08-15
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  • 在线发布日期: 2019-02-14

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