A practical scheme to introduce explicit tidal forcing into an OGCM
A practical scheme to introduce explicit tidal forcing into an OGCM
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DOI：
10.5194/os-9-1089-2013
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发表时间：
2013-12
期刊：
影响因子：
3.2
通讯作者：
K. Sakamoto;H. Tsujino;H. Nakano;Mikitoshi Hirabara;Goro;Yamanaka
中科院分区：
文献类型：
--
作者：
K. Sakamoto;H. Tsujino;H. Nakano;Mikitoshi Hirabara;Goro;Yamanaka
抽象的。提出了一种将潮汐显式引入海洋环流模式（OGCM）的实用方案。在该方案中，正压对潮汐强迫的线性响应由修正的海潮时间微分方程代替了OGCM的正压方程。这允许使用各种参数化指定的潮汐，如自吸引/加载（SAL）的效果和能量耗散由于内部潮汐，而不会无意中违反OGCM中的原始动态平衡。同时，潮汐的二次非线性效应，内潮的激发和潮流的平流，在原始OGCM方程的框架内得到充分的表示。也就是说，该方案驱动OGCM的正压线性潮流，逐步预测的调谐潮汐模型，而不是平衡潮位，没有大的额外的数值成本。我们将此方案应用于气象研究所的社区海洋模式，并在一个低分辨率的全球模式上进行了试验。结果表明，该模式能同时模拟非潮汐环流和潮汐运动。由于使用的潮汐参数化，如SAL项，在潮汐高度的均方根误差被发现是小至10.0厘米，这是精心调整的潮汐模型相媲美。此外，正压潮流的速度和能量的分析发现，与过去的潮汐研究是一致的。该模型还显示了内潮和潮混合的积极兴奋。在未来，内部潮汐和潮汐混合的影响，应使用一个更好的分辨率模型进行检查，因为明确和精确的引入到OGCM潮汐是朝着改进海洋模型的重要一步。
Abstract. A practical scheme is proposed to explicitly introduce tides into ocean general circulation models (OGCM). In this scheme, barotropic linear response to the tidal forcing is calculated by the time differential equations modified for ocean tides, instead of the original barotropic equations of an OGCM. This allows for the usage of various parameterizations specified for tides, such as the self-attraction/loading (SAL) effect and energy dissipation due to internal tides, without unintentional violation of the original dynamical balances in an OGCM. Meanwhile, secondary nonlinear effects of tides, e.g., excitation of internal tides and advection by tidal currents, are fully represented within the framework of the original OGCM equations. That is, this scheme drives the OGCM by the barotropic linear tidal currents which are predicted progressively by a tuned tide model, instead of the equilibrium tide potential, without large additional numerical costs. We incorporated this scheme into Meteorological Research Institute Community Ocean Model and executed test experiments with a low-resolution global model. The results showed that the model can simulate both the non-tidal circulations and the tidal motion simultaneously. Owing to the usage of tidal parameterizations such as a SAL term, a root-mean-squared error in the tidal heights is found to be as small as 10.0 cm, which is comparable to that of elaborately tuned tide models. In addition, analysis of the speed and energy of the barotropic tidal currents is found to be consistent with that of past tide studies. The model also showed active excitement of internal tides and tidal mixing. In the future, the impacts of internal tides and tidal mixing should be examined using a model with a finer resolution, since explicit and precise introduction of tides into an OGCM is a significant step toward the improvement of ocean models.