Mechanisms of Decadal North Atlantic Climate Variability and Implications for the Recent Cold Anomaly
Mechanisms of Decadal North Atlantic Climate Variability and Implications for the Recent Cold Anomaly
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DOI：
10.1175/jcli-d-20-0464.1
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发表时间：
2021-05-01
影响因子：
4.9
通讯作者：
Langehaug, Helene R.
中科院分区：
文献类型：
--
作者：
Arthun, Marius;Wills, Robert C. J.;Langehaug, Helene R.
北大西洋的十年海面温度（SST）波动影响邻近陆地区域的气候，是气候预测技能的主要来源。然而，年代际海温变化的机制仍有待充分了解。本研究利用低频分量分析分离出驱动北大西洋海温十年时间尺度变化的机制，从而识别低频变化的空间和时间结构。基于观测、大型集合历史模拟和工业化前控制模拟，我们确定了北大西洋大气-海洋变化的十年模式，其主导时间尺度为 13-18 年。大范围的大气环流异常通过同期海气热通量和延迟海洋环流变化驱动海温异常，后者涉及经向翻转环流和水平环流。年代际海温异常改变了大气经向温度梯度，导致初始大气环流异常的逆转。变化的时间尺度与斜压罗斯贝波穿过北大西洋副热带向西传播一致。观测到的十年海温变化的时间发展和空间格局与最近观测到的北大西洋副极地变冷是一致的。这表明北大西洋副极地最近的冷异常部分是由年代际海温变化造成的。
Decadal sea surface temperature (SST) fluctuations in the North Atlantic Ocean influence climate over adjacent land areas and are a major source of skill in climate predictions. However, the mechanisms underlying decadal SST variability remain to be fully understood. This study isolates the mechanisms driving North Atlantic SST variability on decadal time scales using low-frequency component analysis, which identifies the spatial and temporal structure of low-frequency variability. Based on observations, large ensemble historical simulations, and preindustrial control simulations, we identify a decadal mode of atmosphere-ocean variability in the North Atlantic with a dominant time scale of 13-18 years. Large-scale atmospheric circulation anomalies drive SST anomalies both through contemporaneous air-sea heat fluxes and through delayed ocean circulation changes, the latter involving both the meridional overturning circulation and the horizontal gyre circulation. The decadal SST anomalies alter the atmospheric meridional temperature gradient, leading to a reversal of the initial atmospheric circulation anomaly. The time scale of variability is consistent with westward propagation of baroclinic Rossby waves across the subtropical North Atlantic. The temporal development and spatial pattern of observed decadal SST variability are consistent with the recent observed cooling in the subpolar North Atlantic. This suggests that the recent cold anomaly in the subpolar North Atlantic is, in part, a result of decadal SST variability.