On the dynamical influence of ocean eddy potential vorticity fluxes
On the dynamical influence of ocean eddy potential vorticity fluxes
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DOI：
10.1016/j.ocemod.2015.06.003
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发表时间：
2015-08
期刊：
影响因子：
3.2
通讯作者：
J. Maddison;D. Marshall;J. Shipton
中科院分区：
文献类型：
--
作者：
J. Maddison;D. Marshall;J. Shipton
涡旋位涡通量对流动动力学演化的影响被大的、动态惰性的旋转通量所掩盖。然而，涡位涡通量分解为旋转和发散分量在有界域中不是唯一的，需要附加边界条件。本文提出在准地转残差平均方程中引入发散涡位涡通量与非发散涡动量趋势的一一对应关系，以选择唯一的发散涡位涡通量。发散涡位涡通量满足零切向分量边界条件。在单连通域中，得到的发散涡位涡通量满足一个强大的最优性条件：它是最小范数的水平方向发散通量。因此，有一种明确的意义，即这种方法尽可能多地去除动态不活跃的涡位涡通量，并提取潜在的动态活跃的发散涡位涡通量。结果表明，通过与平均环流强迫的直接关系，这种方法可以得到发散的涡位涡通量，这种通量具有直观的物理解释。
The impact of eddy potential vorticity fluxes on the dynamical evolution of the flow is obscured by the presence of large and dynamically-inert rotational fluxes. However, the decomposition of eddy potential vorticity fluxes into rotational and divergent components is non-unique in a bounded domain and requires the imposition of an additional boundary condition. Here it is proposed to invoke a one-to-one correspondence between divergent eddy potential vorticity fluxes and non-divergent eddy momentum tendencies in the quasi-geostrophic residual-mean equations in order to select a unique divergent eddy potential vorticity flux. The divergent eddy potential vorticity flux satisfies a zero tangential component boundary condition. In a simply connected domain, the resulting divergent eddy potential vorticity flux satisfies a powerful optimality condition: it is the horizontally oriented divergent flux with minimumL2norm. Hence there is a well-defined sense in which this approach removes as much of the dynamically inactive eddy potential vorticity flux as possible, and extracts an underlying dynamically active divergent eddy potential vorticity flux. It is shown that this approach leads to a divergent eddy potential vorticity flux which has an intuitive physical interpretation, via a direct relationship to the resulting forcing of the mean circulation.