On the validity of downgradient eddy closures in ocean models
On the validity of downgradient eddy closures in ocean models
复制标题
海洋模型中下降涡闭合的有效性
DOI：
10.1029/1999jc000041
复制
发表时间：
2000
影响因子：
--
通讯作者：
D. Marshall
中科院分区：
文献类型：
--
作者：
M. Roberts;D. Marshall
结果是从一个涡旋解决原始方程海洋模式来检验的假设，地转涡旋可以通过各种向下梯度关闭参数化。时间平均涡度通量的温度，等密度厚度，准地转位涡诊断水平表面上从5年的模式数据，并与相应的时间平均梯度的空间相关。我们没有发现明显的相关性之间的绝对涡动通量和平均梯度。然而，分解后的涡动通量为“旋转”和“发散”的组件，我们发现之间的正相关性的发散涡动通量和平均梯度，虽然整体的相关系数仍然很小，通常为O（0.2）。涡动温度通量与平均温度梯度之间的相关性仅在上部2 km为正，在深度为负，表明深海温度通量是双梯度的。相反，涡动通量与等密度厚度和位涡的平均梯度之间的相关性是积极的大部分的流体柱。总的相关性是相似的厚度和位涡关闭。我们进一步分解的涡通量的发散分量的分量垂直和平行于平均轮廓。我们发现垂直分量和平行分量的大小是相似的。
Results are presented from an eddy-resolving primitive equation ocean model to test the hypothesis that geostrophic eddies can be parameterized through a variety of downgradient closures. Time-mean eddy fluxes of temperature, isopycnic thickness, and quasi-geostrophic potential vorticity are diagnosed on level surfaces from 5 years of model data and are spatially correlated with the corresponding time-mean gradients. We find no discernible correlation between the absolute eddy fluxes and mean gradients. However, after decomposing the eddy fluxes into “rotational” and “divergent” components we find a positive correlation between the divergent eddy fluxes and the mean gradients, although the overall correlation coefficients remain small, typically O(0.2). The correlation between the eddy temperature fluxes and mean temperature gradients is positive only over the upper 2 km and is negative at depth, suggesting that the abyssal temperature fluxes are upgradient. In contrast, the correlations between eddy fluxes and mean gradients of isopycnic thickness and potential vorticity are positive over the most of the fluid column. The overall correlations are similar for both thickness and potential vorticity closures. We further decompose the divergent component of the eddy fluxes into components directed perpendicular and parallel to mean contours. We find that both the perpendicular and the parallel components are similar in magnitude.