Low‐frequency interaction between horizontal and overturning gyres in the ocean
Low‐frequency interaction between horizontal and overturning gyres in the ocean
复制标题
海洋中水平环流和翻转环流之间的低频相互作用
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Spall
中科院分区：
文献类型：
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作者：
M. Spall
在理想化的、允许涡流的数值模式中，水平环流的低频变率驱动了纬向翻转环流中低频变率的主导模式。这种耦合是通过气旋性高纬度边界流中的横向平流对沿边界沿着混合层深度的影响而发生的。通过一个诊断估计，可以很好地预测纬向翻转环流的平均和低频变率，该估计假设下降流由沿着边界的混合层内的热风切变控制，而热风切变又由横向平流和地面冷却之间的简单平衡决定。更普遍的结果是证明了纬向翻转流函数的平均和低频变率受沿边界沿着混合层内的斜压梯度控制，这可能受到许多因素的影响，如横向平流的低频变率、风应力、表面浮力通量或冰融化和淡水径流。
Low‐frequency variability of the horizontal circulation in an idealized, eddy‐permitting, numerical model drives the dominant mode of low‐frequency variability in the meridional overturning circulation. This coupling takes place through the influence of lateral advection in the cyclonic high‐latitude boundary current on the mixed layer depth along the boundary. The mean and low‐frequency variability of the meridional overturning circulation are well predicted by a diagnostic estimate that assumes the downwelling is controlled by the thermal wind shear within the mixed layer along the boundary, which is in turn determined by a simple balance between lateral advection and surface cooling. The more general result is the demonstration that the mean and low frequency variability of the meridional overturning streamfunction are controlled by the baroclinic pressure gradient within the mixed layer along the boundary, which may be influenced by numerous factors such as low‐frequency variability in lateral advection, wind stress, surface buoyancy fluxes, or ice melt and freshwater runoff.