Climate Dynamics ( IF 4.6 ) Pub Date : 2022-09-28 , DOI: 10.1007/s00382-022-06445-4 Bingyi Wu, Shuoyi Ding
The Barents-Kara Seas are the crucial regions to link the Arctic to the midlatitudes of Eurasia, and winter warm anomalies around these regions have been regarded as a primary reason for cold-Eurasia over the past decade. Thus, the role of cold-Eurasia in resulting Arctic warm anomalies remains unclear. Through observational analyses and simulation experiments forced by prescribed regional ground albedo in Eurasia, this study shows that cold-Eurasia can give rise to Arctic warm anomalies. Observational analyses suggest that winter warm anomalies over the Barents-Kara Seas are originated from atmospheric circulation anomalies in the mid- and high-latitudes and dominantly associated with the positive NAO and the strengthening of the Siberian high. The strengthened Siberian high well corresponds to a systematic northward shift of atmospheric circulation over northern Eurasia, the North Atlantic, and northern North America, leading to significant increases in the atmospheric total energy transport into the Barents-Kara Seas. All simulation experiments consistently demonstrate that a regional cooling directly contributes to Arctic warm anomalies, and sometimes the cooling enhances the Siberian high and generates positive 500-hPa height anomalies over around the Ural Mountains through atmospheric subsidence anomalies and energy propagations, leading to warm anomalies over the Barents-Kara Seas. The increase in winter Eurasian snow cover, as one of the crucial factors enhancing the ground albedo, would favor the occurrence of warm Arctic-cold Eurasia, and there is already evidence supporting this deduction. This study implies that on the interannual time scales, winter warm anomalies over the Barents-Kara Seas cannot simply be seen as the cause of winter cold-Eurasia.
中文翻译:
冷欧亚大陆导致北极暖异常
巴伦支海-喀拉海是连接北极和欧亚大陆中纬度地区的关键区域,这些地区周围的冬季暖异常一直被认为是过去十年欧亚大陆寒冷的主要原因。因此,冷欧亚大陆在导致北极暖异常中的作用仍不清楚。本研究通过欧亚大陆规定的区域地面反照率强制进行的观测分析和模拟实验,表明欧亚大陆寒冷会引起北极暖异常。观测分析表明,巴伦支海冬季暖异常起源于中高纬度地区的大气环流异常,主要与正NAO和西伯利亚高压增强有关。加强的西伯利亚高井对应于欧亚大陆北部、北大西洋和北美北部大气环流系统性向北移动,导致大气总能量输送显着增加进入巴伦支海-喀拉海。所有模拟实验一致表明,区域降温直接导致北极暖异常,有时降温增强了西伯利亚高压,并通过大气沉降异常和能量传播在乌拉尔山脉周围产生 500 hPa 正高度异常,从而导致暖异常巴伦支-喀拉海。欧亚大陆冬季积雪的增加是提高地面反照率的关键因素之一,有利于暖北极-寒冷欧亚大陆的出现,并且已经有证据支持这一推论。这项研究表明,在年际时间尺度上,巴伦支海-喀拉海的冬季暖异常不能简单地被视为欧亚大陆冬季寒冷的原因。