Towards a parametrization of river discharges into ocean general circulation models: a closure through energy conservation
Towards a parametrization of river discharges into ocean general circulation models: a closure through energy conservation
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将河流流量参数化纳入海洋环流模型：通过节能进行封闭
DOI：
10.1007/s00382-008-0416-4
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
G. Madec
中科院分区：
文献类型：
--
作者：
R. Hordoir;J. Polcher;J. Brun;G. Madec
定义了诊断方法，以便比较淡水影响区域内海洋动力学的两个数值模拟。第一个是基于POM沿海海洋模式的高分辨率数值配置的河流羽流模拟，其中混合参数已经预先定义。第二个是基于NEMO全球海洋模型的模拟，该模型用于半度配置的气候模拟，其中河流流入被表示为两个沿海网格单元的降水。两种模拟都是在相同的淡水流入和风应力的作用下进行的。比较了盐斜上、盐斜下体积通量的散度。结果表明，当有上升风吹起时，两种模型表现出相似的行为，尽管在NEMO配置中可以观察到缺乏精度的影响。当下流风吹起时，NEMO全球海洋结构不能重现沿海捕获的斜压动力学，因为它的网格分辨率太粗。为了在海洋环流模式中找到一种参数化方法来表示这些动力学，本文研究了一种基于能量守恒的方法。该方法表明，将河流流入提供的能量通量与海洋环流模式网格单元上积分的能量通量发散联系起来是可能的。从该方法推导出淡水流入所产生的动力学参数化。这样可以创建一个盒状模型，该模型被证明具有与以前从高分辨率配置计算的通量相同的行为。
Diagnostic methods are defined in order to compare two numerical simulations of ocean dynamics in a region of freshwater influence. The first one is a river plume simulation based on a high resolution numerical configuration of the POM coastal ocean model in which mixing parametrizations have been previously defined. The second one is a simulation based on the NEMO Global Ocean Model used for climate simulations in its half-a-degree configuration in which a river inflow is represented as precipitation on two coastal grid cells. Both simulations are forced with the same freshwater inflows and wind stresses. The divergence of volumetric fluxes above and below the halocline are compared. Results show that when an upwelling wind blows, the two models display similar behavior although the impact of lack of precision can be observed in the NEMO configuration. When a downwelling wind blows, the NEMO Global Ocean configuration can not reproduce the coastally trapped baroclinic dynamics because its grid resolution is too coarse. To find a parametrization to help represent these dynamics in ocean general circulation models, a method based on energy conservation is investigated. This method shows that it is possible to link the energy fluxes provided by river inflows to the divergence of energy fluxes integrated over the grid cells of ocean general circulation models. A parametrization of the dynamics created by freshwater inflows is deduced from this method. This enabled creation of a box model that proved to have the same behavior as the fluxes previously computed from the high resolution configuration.