Interannual to decadal Gulf Stream variability in an eddy-resolving ocean model
Interannual to decadal Gulf Stream variability in an eddy-resolving ocean model
复制标题
涡旋分辨海洋模型中墨西哥湾流的年际至年代际变化
DOI：
10.1016/j.ocemod.2011.04.004
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发表时间：
2011
期刊：
影响因子：
3.2
通讯作者：
N.Schneider
中科院分区：
文献类型：
--
作者：
Sasaki;Y.N.;N.Schneider
利用一个近全球涡旋分辨率海洋模式的后播，研究了1960-2003年墨西哥湾流急流在年际到年代际时间尺度上的经向移位及其周围的海洋变化。模拟得到的GS急流轴的变化与观测结果吻合较好，比以北大西洋涛动为特征的大气波动滞后了约2年。GS急流对大气变化的滞后响应归因于急流轴从45°W到75°W的波动向西传播，它的波长约为4000公里，位移为0.5°。约2.8 cm的−1的传播方向和相速度符合薄喷流理论。下游地区急流轴线的移动可能是由北大西洋中部的埃克曼辐合引起的风波动引起的。与急流轴线北(南)移相关的是急流周围和北部海温的增温(降温)，前者增温具有较深的经向窄的次表层结构，与急流的北移相一致。喷流的经向位移伴随着GS周围高能涡旋活动区的相干经向位移。我们的数值结果表明，GS急流将大气信号从北大西洋中心带到北大西洋西部，由此引起的急流经向位移引起了GS周围显著的海洋变化。
Meridional shifts of the Gulf Stream (GS) jet on interannual to decadal timescales and the corresponding oceanic changes around the GS are investigated using a near global eddy-resolving ocean model hindcast from 1960 to 2003. The simulated variability in the shifts of the GS jet axis shows good agreement with observations, and lags atmospheric fluctuations characterized by the North Atlantic Oscillation by about 2years. This lagged response of the GS jet to the atmospheric variations is attributed to the westward propagation of the undulation of the jet axis from 45°W to 75°W, which has a wavelength of about 4000km and a displacement of 0.5°. The propagation direction and phase speed of about 2.8cms−1are consistent with the thin-jet theory. The shifts of the jet axis in the downstream region are likely induced by wind fluctuations through Ekman convergence over the central North Atlantic. Associated with the northward (southward) shift of the jet axis, sea surface temperature is warming (cooling) around and north of the jet, and the former warming has a deep and meridionally narrow subsurface structure, consistent with the northward shift of the jet. The meridional shifts of the jet accompany coherent meridional shifts of energetic eddy activity regions around the GS. Our numerical results suggest that the GS jet brings the atmospheric signals from the central to the western North Atlantic, and the resultant meridional shift of the jet induces the notable oceanic changes around the GS.