Abstract Resonant triad interaction is an important mechanism via which the energy of internal tides (ITs) is dissipated. In this study, based on a two-dimensional high-resolution non-hydrostatic model, resonant triad interaction over mid-ocean ridges and corresponding energetics are investigated. Impacts of topographic criticality (the ratio of topographic slope to internal wave slope) on resonant triad interaction are examined by a series of simulations. Results indicate that the topographic criticality not only affects the occurrence of resonant triad interaction but also modulates the frequencies of generated subharmonic waves. Near-critical and supercritical topographies are beneficial to the occurrence of resonant triad interaction with enhanced energy production and dissipation. The impacts of topographic criticality are modulated by latitude. At the critical latitude where local Coriolis frequency is equal to half of the tidal frequency, subharmonic waves are intensified over critical and subcritical topographies, but their frequencies are fixed to local Coriolis frequency. In contrast, resonant triad interaction is suppressed poleward of the critical latitude despite the topographic criticality. Although the energy of subharmonic waves is less than a quarter of the total energy, they contribute to 50% of the total energy dissipation on average. Given that global ITs are dominated by the M 2 and most of the M 2 ITs are generated upon mid-ocean ridges equatorward of the critical latitude, a remarkable proportion of global IT energy may be dissipated through resonant triad interaction. Therefore, the contribution of resonant triad interaction should be taken into consideration when developing the parameterization of IT-driven mixing.

中文翻译：

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大洋中脊上的共振三元组相互作用

摘要 共振三元组相互作用是内部潮汐（ITs）能量耗散的重要机制。在这项研究中，基于二维高分辨率非流体静力模型，研究了大洋中脊上的共振三元组相互作用和相应的能量学。地形临界性（地形坡度与内部波浪坡度的比值）对共振三元组相互作用的影响通过一系列模拟进行检查。结果表明，地形临界性不仅影响共振三元组相互作用的发生，而且还调制产生的次谐波的频率。近临界和超临界形貌有利于发生与增强的能量产生和耗散的共振三元组相互作用。地形临界性的影响受纬度调节。在局部科里奥利频率等于潮汐频率一半的临界纬度，次谐波在临界和亚临界地形上增强，但它们的频率固定为局部科里奥利频率。相比之下，尽管地形临界，共振三元组相互作用在临界纬度的两极被抑制。次谐波的能量虽然不到总能量的四分之一，但平均占总能量耗散的 50%。鉴于全球 IT 以 M 2 为主，并且大部分 M 2 IT 产生于临界纬度赤道附近的洋中脊，全球 IT 能量的显着比例可能会通过共振三元组相互作用耗散。所以，