Interfacial Form Stress in the Southern Ocean State Estimate
Interfacial Form Stress in the Southern Ocean State Estimate
复制标题
南大洋状态估计中的界面形式应力
DOI：
10.1029/2018jc013844
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发表时间：
2018
影响因子：
--
通讯作者：
T. Chereskin
中科院分区：
文献类型：
--
作者：
J. Masich;M. Mazloff;T. Chereskin
驱动南极绕极流(ACC)的风应力通过海底的地形形应力(TFS)离开流体；界面形应力(IFS)被认为携带了大部分动量从源头到下沉。这些形式的应力结合在一起，有助于确定南大洋经向翻转环流(MOC)的强度和结构，MOC是深海和大气之间热量和气体交换的关键纽带。在大气环流模式中，我们首次从等厚层界面垂直扰动的纬向气压梯度直接计算了时变的三维IFS场。我们证实了以前的研究结果，即在德雷克航道纬度，迭代函数系统补偿了表面的风应力和海底的地形形应力。研究发现，纬向风场和时间平均风场对地面风应力的补偿起主要作用，瞬变涡动风场也有一定的贡献。平均、定涡和瞬变涡旋迭代函数系统结合起来补偿了深部地形形成的应力。驻留和瞬变涡旋迭代函数系统都集中在ACC沿线的静止弯道，而瞬变涡旋迭代函数系统在涡动动能高的区域占主导地位。最后，在28.1 kg m附近，浮力强迫作用在南极底水上限附近由平衡东向风应力向平衡西向地形形应力变化，表明浮力强迫在决定场型结构中的作用。南大洋上的风向东吹，不断向东向海洋输入动量。这种向东的势头被阻止南极绕极流的陆块和海底海脊所平衡，S说，这些海脊阻挡了绕南极向东的路径。我们分析了一个高分辨率的南大洋模式来绘制界面形应力(IFS)，即动量从风源到海底下沉的机制。我们以一种新的、独特的方式进行这一分析，通过计算在6年模型运行中每天从一个海洋层到另一个海洋层施加的压力；这种分析显示了较轻的海洋层对较密集的海洋层“倾斜”的地方，从而将向东的动量从较轻的海洋层向下转移到较密集的海洋层。我们发现，该系统主要集中在ACC中有大范围弯曲的地方，在南大洋有涡旋混合的地区也有较小程度的集中。
The wind stress that drives the Antarctic Circumpolar Current (ACC) exits the fluid via topographic form stress (TFS) at the sea floor; interfacial form stress (IFS) is thought to carry much of this momentum from source to sink. These form stresses combine to help set the strength and structure of the Southern Ocean meridional overturning circulation (MOC), a key nexus of heat and gas exchange between the deep ocean and the atmosphere. For the first time in a general circulation model, we calculate the timevarying, three-dimensional IFS field directly from zonal pressure gradients across vertical perturbations in isopycnal layer interfaces. We confirm previous findings that IFS compensates wind stress at the surface and topographic form stress at the seafloor in the Drake Passage latitudes. We find that zonal and time-mean IFS is primarily responsible for this surface wind stress compensation, with some contribution from transient eddy IFS. Mean, standing eddy, and transient eddy IFS combine to compensate topographic form stress at depth. Both standing and transient eddy IFS concentrate at stationary meanders along the ACC, and transient eddy IFS dominates standing eddy IFS in regions of high eddy kinetic energy. Finally, total IFS changes sign from balancing eastward wind stress to balancing westward topographic form stress around 28.1 kg m, close to the upper limit of Antarctic Bottom Water, indicating the role of buoyancy forcing in setting the structure of the IFS field. Plain Language Summary Winds over the Southern Ocean blow toward the east, continuously inputting eastward momentum into the ocean. This eastward momentum is balanced by the landmasses and undersea ridges that block the Antarctic Circumpolar Current (ACC)’s eastward path around Antarctica. We analyze a high-resolution model of the Southern Ocean to map interfacial form stress (IFS), the mechanism by which momentum travels from wind source to seafloor sink. We conduct this analysis in a new, unique way, by calculating the pressure exerted from one ocean layer to another for every day in the 6 year model run; this analysis shows where lighter layers are ‘‘leaning’’ against denser layers and thus transferring eastward momentum downward from lighter to denser ocean layers. We find that IFS mostly concentrates where there are large-scale meanders in the ACC, and to a lesser degree in regions where the Southern Ocean is mixed by eddies.
影响因子：
3.5
作者：
A. Thompson;A. N. Garabato
通讯作者：
A. Thompson;A. N. Garabato
影响因子：
3.5
作者：
Howard E
通讯作者：
Howard E