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How do intermittency and simultaneous processes obfuscate the Arctic influence on midlatitude winter extreme weather events?
Environmental Research Letters ( IF 6.7 ) Pub Date : 2021-03-18 , DOI: 10.1088/1748-9326/abdb5d
J E Overland 1 , T J Ballinger 2 , J Cohen 3, 4 , J A Francis 5 , E Hanna 6 , R Jaiser 7 , B -M Kim 8 , S -J Kim 9 , J Ukita 10 , T Vihma 11 , M Wang 1, 12 , X Zhang 2
Affiliation  

Pronounced changes in the Arctic environment add a new potential driver of anomalous weather patterns in midlatitudes that affect billions of people. Recent studies of these Arctic/midlatitude weather linkages, however, state inconsistent conclusions. A source of uncertainty arises from the chaotic nature of the atmosphere. Thermodynamic forcing by a rapidly warming Arctic contributes to weather events through changing surface heat fluxes and large-scale temperature and pressure gradients. But internal shifts in atmospheric dynamics—the variability of the location, strength, and character of the jet stream, blocking, and stratospheric polar vortex (SPV)—obscure the direct causes and effects. It is important to understand these associated processes to differentiate Arctic-forced variability from natural variability. For example in early winter, reduced Barents/Kara Seas sea-ice coverage may reinforce existing atmospheric teleconnections between the North Atlantic/Arctic and central Asia, and affect downstream weather in East Asia. Reduced sea ice in the Chukchi Sea can amplify atmospheric ridging of high pressure near Alaska, influencing downstream weather across North America. In late winter southward displacement of the SPV, coupled to the troposphere, leads to weather extremes in Eurasia and North America. Combined tropical and sea ice conditions can modulate the variability of the SPV. Observational evidence for Arctic/midlatitude weather linkages continues to accumulate, along with understanding of connections with pre-existing climate states. Relative to natural atmospheric variability, sea-ice loss alone has played a secondary role in Arctic/midlatitude weather linkages; the full influence of Arctic amplification remains uncertain.



中文翻译:

间歇性和同时性过程如何混淆北极对中纬度冬季极端天气事件的影响?

北极环境的显着变化增加了影响数十亿人的中纬度地区异常天气模式的新潜在驱动因素。然而,最近对这些北极/中纬度天气联系的研究却得出了不一致的结论。不确定性的来源来自大气的混乱性质。北极迅速变暖的热力学强迫通过改变地表热通量和大尺度的温度和压力梯度来促成天气事件。但是大气动力学的内部变化——急流、阻塞和平流层极涡 (SPV) 的位置、强度和特征的变化——掩盖了直接的原因和影响。了解这些相关过程以区分北极强迫变率和自然变率非常重要。比如初冬,巴伦支海/喀拉海海冰覆盖范围的减少可能会加强北大西洋/北极和中亚之间现有的大气遥相关,并影响东亚的下游天气。楚科奇海的海冰减少可以放大阿拉斯加附近的高压大气脊,影响整个北美的下游天气。在冬末,SPV 向南位移,加上对流层,导致欧亚大陆和北美出现极端天气。结合热带和海冰条件可以调节 SPV 的可变性。北极/中纬度天气联系的观测证据继续积累,同时了解与预先存在的气候状态的联系。相对于自然大气变率,仅海冰损失就在北极/中纬度天气联系中发挥了次要作用;

更新日期:2021-03-18
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