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Global Dynamics of the Stationary M2 Mode-1 Internal Tide
Samuel M Kelly1, Amy F Waterhouse2, Anna C Savage2
1Large Lakes Observatory and Physics & Astronomy Department University of Minnesota Duluth Duluth MN USA.
Geophysical Research Letters
|July 5, 2021
Summary
This study uses a reduced-physics model to simulate the M2 internal tide, finding it generates 200 GW of energy. The model accurately reproduces observed sea-surface height, with most energy lost to dissipation and non-stationary processes.
Area of Science:
- Oceanography
- Fluid Dynamics
- Geophysics
Background:
- Internal tides play a crucial role in ocean mixing and energy dissipation.
- Understanding their generation and propagation is key to accurate ocean modeling.
Purpose of the Study:
- To determine if linear dynamics can reproduce observed low-mode M2 internal tides.
- To assess internal tide sensitivity to bathymetry, stratification, surface tides, and dissipation.
- To quantify power transfer to the non-stationary internal tide.
Main Methods:
- Employed a reduced-physics model at high global resolutions (1/25° to 1/100°).
- Incorporated parameterizations for wave drag and wave-mean interaction.
- Analyzed simulation energy balance and energy transfer pathways.
Main Results:
- Predicted 200 GW of mode-1 internal tide generation, aligning with GCMs and theory.
- Simulations captured 84% of satellite-observed sea-surface height variance.
- Identified energy loss mechanisms: 54% to high-mode scattering and 29% to non-stationary internal tides.
Conclusions:
- Linear dynamics are capable of reproducing key features of the M2 internal tide.
- Dissipation and non-stationary processes significantly impact internal tide energy.
- The model provides a robust framework for studying internal tide dynamics and their impact on ocean circulation.
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