Impact of Ural Blocking on Winter Warm Arctic-Cold Eurasian Anomalies. Part I: Blocking-Induced Amplification
Impact of Ural Blocking on Winter Warm Arctic-Cold Eurasian Anomalies. Part I: Blocking-Induced Amplification
复制标题
乌拉尔阻塞对冬季温暖的北极 - 寒冷的欧亚异常的影响。
DOI：
10.1175/jcli-d-15-0611.1
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发表时间：
2016-06-01
影响因子：
4.9
通讯作者：
Franzke, Christian L. E.
中科院分区：
文献类型：
--
作者：
Luo, Dehai;Xiao, Yiqing;Franzke, Christian L. E.
在本研究的第一部分中，乌拉尔阻塞（UB）对1979-2013年期间与冬季（DJF）北极海冰损失相关的暖北极-冷欧亚（WACE）模式的影响通过将北极海冰减少区域划分为两个主要子区域进行了研究：巴伦支海和喀拉海（BKS）以及北美高纬度（NAH）地区（巴芬湾和哈德逊湾、戴维斯海峡和拉布拉多海）。结果表明，大气对北极海冰损失的响应类似于一个负的北极响应振荡，欧亚亚北极地区的高度距平主要为正。两个分区的回归分析进一步表明，BKS海冰损失对应于UB型和正的北大西洋涛动（NAO（+）），随后是WACE异常，而NAH区海冰减少对应负NAO（NAO（-））进一步的分析表明，UB型在2000-13年（P2）比1979-99年（P1）由于与强烈的BKS变暖相关的欧亚大陆中高纬平均西风减少。在P2期间，由于BKS变暖的作用，UB的建立成为一个缓慢的过程，而其衰减则稍快。在NAO（+）常出现的长周期UB的存在下，BKS暖化引起的DJF平均反气旋异常在P2期间得到加强和加宽，然后向南扩展，扩大WACE型，并导致其冷异常向南位移和BKS海冰的进一步损失。因此，中纬度欧亚冷事件应该更频繁的海冰损失继续在BKS。
In Part I of this study, the impact of Ural blocking (UB) on the warm Arctic-cold Eurasian (WACE) pattern associated with the winter (DJF) arctic sea ice loss during 1979-2013 is examined by dividing the arctic sea ice reduction region into two dominant subregions: the Barents and Kara Seas (BKS) and the North American high-latitude (NAH) region (Baffin and Hudson Bay, Davis Strait, and Labrador Sea). It is found that atmospheric response to arctic sea ice loss resembles a negative Arctic response oscillation with a dominant positive height anomaly over the Eurasian subarctic region. Regression analyses of the two subregions further show that the sea ice loss over the BKS corresponds to the UB pattern together with a positive North Atlantic Oscillation (NAO(+)) and is followed by a WACE anomaly, while the sea ice reduction in the NAH region corresponds to a negative NAO (NAO(-)) pattern with a cold anomaly over northern Eurasia.Further analyses reveal that the UB pattern is more persistent during the period 2000-13 (P2) than 1979-99 (P1) because of the reduced middle-to-high-latitude mean westerly winds over Eurasia associated with the intense BKS warming. During P2 the establishment of the UB becomes a slow process because of the role of the BKS warming, while its decay is slightly rapid. In the presence of the long-lived UB that often occurs with the NAO(+), the BKS-warming-induced DJF-mean anticyclonic anomaly is intensified and widened and then expands southward during P2 to amplify the WACE pattern and induce the southward displacement of its cold anomaly and the further loss of the BKS sea ice. Thus, midlatitude Eurasian cold events should be more frequent as the sea ice loss continues over the BKS.