Impacts of Arctic Sea Ice on Cold Season Atmospheric Variability and Trends Estimated from Observations and a Multi-model Large Ensemble
Impacts of Arctic Sea Ice on Cold Season Atmospheric Variability and Trends Estimated from Observations and a Multi-model Large Ensemble
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DOI：
10.1175/jcli-d-20-0578.1
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发表时间：
2021-08
影响因子：
4.9
通讯作者：
Yu‐Chiao Liang;C. Frankignoul;Young‐Oh Kwon;G. Gastineau;E. Manzini;G. Danabasoglu;L. Suo;S. Yeager;Yongqi Gao;J. Attema;A. Cherchi;R. Ghosh;D. Matei;J. Mecking;T. Tian;Ying Zhang
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文献类型：
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作者：
Yu‐Chiao Liang;C. Frankignoul;Young‐Oh Kwon;G. Gastineau;E. Manzini;G. Danabasoglu;L. Suo;S. Yeager;Yongqi Gao;J. Attema;A. Cherchi;R. Ghosh;D. Matei;J. Mecking;T. Tian;Ying Zhang
研究大气对北方冷季北极海冰变化的响应（10月至次年3月），这项研究使用了9个大气环流模式（AGCM）的一组协调的大型集合实验，强迫观测到1979-2014年期间每日变化的海冰，海面温度和辐射强迫，以及一组平行的实验，其中北极海冰被其气候学所取代。前一组的模拟再现近地表温度的趋势再分析数据，具有相似的幅度，和他们的多模式集合平均（MMEM）显示减少海平面压力在极地帽和欧亚大陆的北部秋季。这两个实验之间的MMEM差异允许隔离北极海冰损失的影响，这解释了对流层下部北极变暖趋势的很大一部分，并驱动了一个小的，但统计上显着的冬季北极涛动减弱。观测到的海冰范围之间的年际协变在巴伦支-卡拉海和滞后大气环流的影响区分的混杂因素的基础上的多元回归，并定量地比较MMEMs的协变。观测中发现的负北大西洋振荡样异常的年际海冰下降也出现在MMEM差异中，具有一致的空间结构，但幅度要小得多。这一结果表明，海冰对AGCM模拟的趋势和年际大气变率的影响可能被低估，但需要谨慎，因为内部大气变率可能影响了观测到的关系。
To examine the atmospheric responses to Arctic sea-ice variability in the Northern Hemisphere cold season (October to following March), this study uses a coordinated set of large-ensemble experiments of nine atmospheric general circulation models (AGCMs) forced with observed daily-varying sea-ice, sea-surface temperature, and radiative forcings prescribed during the 1979-2014 period, together with a parallel set of experiments where Arctic sea ice is substituted by its climatology. The simulations of the former set reproduce the near-surface temperature trends in reanalysis data, with similar amplitude, and their multi-model ensemble mean (MMEM) shows decreasing sea-level pressure over much of the polar cap and Eurasia in boreal autumn. The MMEM difference between the two experiments allows isolating the effects of Arctic sea-ice loss, which explain a large portion of the Arctic warming trends in the lower troposphere and drives a small but statistically significant weakening of the wintertime Arctic Oscillation. The observed interannual co-variability between sea-ice extent in the Barents-Kara Seas and lagged atmospheric circulation is distinguished from the effects of confounding factors based on multiple regression, and quantitatively compared to the co-variability in MMEMs. The interannual sea-ice decline followed by a negative North Atlantic Oscillation-like anomaly found in observations is also seen in the MMEM differences, with consistent spatial structure but much smaller amplitude. This result suggests that the sea-ice impacts on trends and interannual atmospheric variability simulated by AGCMs could be underestimated, but caution is needed because internal atmospheric variability may have affected the observed relationship.