Reconstructing the meridional overturning circulation from boundary densities and the zonal wind stress
Reconstructing the meridional overturning circulation from boundary densities and the zonal wind stress
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DOI：
10.1175/jpo3019.1
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发表时间：
2007-03-01
影响因子：
3.5
通讯作者：
Marotzke, J.
中科院分区：
文献类型：
--
作者：
Hirschi, J.;Marotzke, J.
利用数值模式验证了边界层密度和风应力能否重建涡旋翻转环流。在没有地形的理想模式设置中，MOC单元的强度以及时间和空间变化可以在很大程度上从边界密度和纬向风应力中再现。随着沿纬向边界沿着增加坡度，大部分深度平均流被忽略，MOC的强度和空间结构都不能很好地再现。然而，两者的MOC和它的估计的时间演变是相似的。在具有真实海底地形的涡流允许模型中，深度平均纬向流对MOC的贡献在某些地方被捕获，而在其他地方则被忽略。然而，边界密度和纬向风应力允许的时间和空间的MOC变率的主导模式被复制。在季节时间尺度上，大部分的MOC的变化是由于风应力，但边界密度的变化影响MOC以及。在年际时间尺度上，MOC的变化在很大程度上反映了边界密度的变化。通常，当底部速度较小时，MOC重建是准确的，这是重建方法中的一个假设。结果是相关的现代和过去的MOC的估计。在真实的海洋中，边界密度可以通过测量水柱中的温度、电导率和压力来获得，而过去的海水密度在海洋沉积物中留下了印记。
Numerical models are used to test whether the meridional overturning circulation (MOC) can be reconstructed from boundary densities and the wind stress. In idealized model setups without topography the strength as well as the temporal and spatial variability of the MOC cell can largely be reproduced from boundary densities and the zonal wind stress. With added slopes along the meridional boundaries, most of the depth-averaged flow is missed and neither strength nor spatial structure of the MOC is well reproduced. However, the temporal evolution of both MOC and its estimate are similar. In an eddy-permitting model with realistic bottom topography the contribution of the depth-averaged meridional flow to the MOC is captured at some places while it is missed at others. Nevertheless, boundary densities and the zonal wind stress allow the leading modes of the temporal and spatial MOC variability to be reproduced. On seasonal time scales most of the MOC variability is due to the wind stress but changes in the boundary density affect the MOC as well. On interannual time scales the MOC variability largely reflects changes in the boundary density. Generally, the MOC reconstructions are accurate when bottom velocities are small, an assumption made in the reconstruction approach. The results are relevant for estimates of both the modern and the past MOC. In the real ocean, boundary densities can be obtained from measurements of temperature, conductivity, and pressure in the water column, whereas past seawater densities have left their imprint in sea sediments.