Abstract The potential influence of a developing La Niña on Arctic sea-ice annual variability is investigated using both observational data and an atmospheric general circulation model. It is found that during the developing phase of an eastern Pacific (EP) La Niña event in June, July, and August (JJA) and September, October, and November (SON), the sea-ice concentration (SIC) over the Barents–Kara Seas declines more than 15%. The local atmospheric circulation pattern associated with the EP La Niña is characterized as a weak decrease in geopotential height over the Barents–Kara Seas, combined with an anticyclone in the North Atlantic. The corresponding southerly winds push warm waters northward into the key sea-ice reduction region and directly accelerate sea-ice melt. Meanwhile, the abundant moisture contained in the lower troposphere is transported into the Arctic region by winds resulting from the local barotropic structure. The humid atmosphere contributes to both net shortwave and longwave radiation and thus indirectly accelerates the decline in sea ice. Simulations by the European Centre Hamburg Model, version 5.4, are forced by observed sea surface temperature anomalies associated with EP La Niña events. The results of the simulations capture the North Atlantic anticyclone and reproduce the moisture transport, which supports the premise that an EP La Niña plays a crucial role in sea-ice reduction over the Barents–Kara sector from the perspective of atmospheric circulation and net surface heat flux.

中文翻译：

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发展中的拉尼娜现象对巴伦支海-喀拉海海冰减少的潜在影响

摘要 利用观测数据和大气环流模型研究了发展中的拉尼娜现象对北极海冰年变率的潜在影响。研究发现，在东太平洋（EP）6、7、8月（JJA）和9、10、11月（SON）拉尼娜事件发展阶段，巴伦支海的海冰浓度（SIC） –Kara Seas 跌幅超过 15%。与 EP 拉尼娜现象相关的局地大气环流模式的特点是巴伦支海-卡拉海的位势高度微弱下降，同时北大西洋出现反气旋。相应的南风将暖水向北推入海冰减少的关键区域，直接加速海冰融化。同时，低层对流层中丰富的水分被当地正压结构产生的风输送到北极地区。潮湿的大气对净短波和长波辐射都有贡献，从而间接加速了海冰的减少。欧洲中心汉堡模型 5.4 版的模拟是由观测到的与 EP 拉尼娜事件相关的海面温度异常所强迫的。模拟结果捕获了北大西洋反气旋并再现了水分输送，这支持了从大气环流和净地表热量的角度来看，EP 拉尼娜对巴伦支海-卡拉区海冰减少起到关键作用的假设通量。潮湿的大气对净短波和长波辐射都有贡献，从而间接加速了海冰的减少。欧洲中心汉堡模型 5.4 版的模拟是由观测到的与 EP 拉尼娜事件相关的海面温度异常所强迫的。模拟结果捕捉到了北大西洋反气旋并再现了水分输送，这支持了从大气环流和净地表热量的角度来看，EP 拉尼娜现象在巴伦支海-卡拉海区减少海冰方面发挥关键作用的假设通量。潮湿的大气对净短波和长波辐射都有贡献，从而间接加速了海冰的减少。欧洲中心汉堡模型 5.4 版的模拟是由观测到的与 EP 拉尼娜事件相关的海面温度异常所强迫的。模拟结果捕获了北大西洋反气旋并再现了水分输送，这支持了从大气环流和净地表热量的角度来看，EP 拉尼娜对巴伦支海-卡拉区海冰减少起到关键作用的假设通量。