Response of Arctic Freshwater to the Arctic Oscillation in Coupled Climate Models
Response of Arctic Freshwater to the Arctic Oscillation in Coupled Climate Models
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DOI：
10.1175/jcli-d-19-0685.1
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发表时间：
2020-04-01
影响因子：
4.9
通讯作者：
Lique, Camille
中科院分区：
文献类型：
--
作者：
Cornish, Sam B.;Kostov, Yavor;Lique, Camille
北冰洋的淡水含量（FWC）与北冰洋的层化密切相关，层化是北冰洋的一个物理特征，与气候和生物学有着广泛的相关性。在这里，我们探讨了大气环流和北极FWC之间的关系，在12个不同的控制运行模拟耦合模式相互比较项目的第5阶段。使用多元滞后回归，我们试图隔离北极FWC的线性响应的北极涛动（AO）的强度，以及在北极域的SLP变化的第二和第三正交模式的一个步骤的变化。有一个更反气旋AO的阶跃变化导致北极FWC的增加，与e折叠时间尺度为5-10年的模式之间的广泛协议。然而，模型差异很大，在何种程度上的线性响应SLP变异可以解释FWC的变化。虽然平均状态，时间尺度和FWC变化的幅度可能是大致相似的，物理起源的变化是高度不一致的模型。我们进行了一个稳健性测试，采用蒙特卡罗方法来确定哪些响应函数最有可能代表模型中的因果关系和物理关系，哪些是回归的工件。卷积与SLP再分析数据表明，四个最强大的响应函数有一定的技巧，在再现所观察到的积累FWC在20世纪90年代末和21世纪初，一致的想法，这种变化主要是风驱动的。
The freshwater content (FWC) of the Arctic Ocean is intimately linked to the stratification-a physical characteristic of the Arctic Ocean with wide relevance for climate and biology. Here, we explore the relationship between atmospheric circulation and Arctic FWC across 12 different control-run simulations from phase 5 of the Coupled Model Intercomparison Project. Using multiple lagged regression, we seek to isolate the linear response of Arctic FWC to a step change in the strength of the Arctic Oscillation (AO) as well as the second and third orthogonal modes of SLP variability over the Arctic domain. There is broad agreement among models that a step change to a more anticyclonic AO leads to an increase in Arctic FWC, with an e-folding time scale of 5-10 yr. However, models differ widely in the degree to which a linear response to SLP variability can explain FWC changes. Although the mean states, time scales, and magnitudes of FWC variability may be broadly similar, the physical origins of variability are highly inconsistent among models. We perform a robustness test that incorporates a Monte Carlo approach to determine which response functions are most likely to represent causal, physical relationships within the models and which are artifacts of regression. Convolution with SLP reanalysis data shows that the four most robust response functions have some skill at reproducing observed accumulation of FWC during the late 1990s and 2000s, consistent with the idea that this change was largely wind driven.