Global Atmospheric Teleconnections and Multidecadal Climate Oscillations Driven by Southern Ocean Convection
Global Atmospheric Teleconnections and Multidecadal Climate Oscillations Driven by Southern Ocean Convection
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DOI：
10.1175/jcli-d-16-0741.1
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发表时间：
2017-10-01
影响因子：
4.9
通讯作者：
Gnanadesikan, Anand
中科院分区：
文献类型：
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作者：
Cabre, Anna;Marinov, Irina;Gnanadesikan, Anand
地球物理流体动力学实验室 (GFDL) 气候模型系列的低分辨率大气-海洋耦合模型的 1000 年控制模拟显示，南大洋 (SO) 公海对流周期和非对流周期之间存在自然、高度规则的数十年振荡。这里显示，对流周期与 SO 海面温度 (SST) 的变暖有关，更广泛地说，与南半球 (SH) SST 和大气温度的变暖有关。 SO变暖导致南半球海温经向梯度减小，改变了大范围的气压模式，降低了中纬度斜压性，从而降低了南费雷尔环流圈和哈德来环流的强度，减弱了SO西风和南半球热带信风。大气环流的重新排列与全球能量平衡是一致的。在对流几十年期间，南半球大气层顶部传入辐射的增加与北半球（NH）传出辐射的增加相平衡。随着热带辐合带和相关的风型向南移动，朝向异常温暖的南半球，提供这种增加的能量是由穿过赤道的增强的大气输送携带的。虽然SO对长期古气候时间尺度上的气候的关键作用现已无可争议，但这里观察到的遥相关的强度和全球范围也表明SO在较短的年际和数十年时间尺度上的全球气候动态中发挥着重要作用。
A 1000-yr control simulation in a low-resolution coupled atmosphere-ocean model from the Geophysical Fluid Dynamics Laboratory (GFDL) family of climate models shows a natural, highly regular multidecadal oscillation between periods of Southern Ocean (SO) open-ocean convection and nonconvective periods. It is shown here that convective periods are associated with warming of the SO sea surface temperatures (SSTs), and more broadly of the Southern Hemisphere (SH) SSTs and atmospheric temperatures. This SO warming results in a decrease in the meridional gradient of SSTs in the SH, changing the large-scale pressure patterns, reducing the midlatitude baroclinicity and thus the magnitude of the southern Ferrel and Hadley cells, and weakening the SO westerly winds and the SH tropical trade winds. The rearrangement of the atmospheric circulation is consistent with the global energy balance. During convective decades, the increase in incoming top-of-the-atmosphere radiation in the SH is balanced by an increase in the Northern Hemisphere (NH) outgoing radiation. The energy supplying this increase is carried by enhanced atmospheric transport across the equator, as the intertropical convergence zone and associated wind patterns shift southward, toward the anomalously warmer SH. While the critical role of the SO for climate on long, paleoclimate time scales is now beyond debate, the strength and global scale of the teleconnections observed here also suggest an important role for the SO in global climate dynamics on the shorter interannual and multidecadal time scales.