Numerical modelling of surface and internal tides

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• Vladimir Lapin (Leeds)
• Monday 27 January 2014, 14:00-15:00
• Watson LRA.

If you have a question about this talk, please contact Alexandra Tzella.

Almost 250 years ago Laplace formulated a system of linear PDEs governing the dynamics of ocean tides given astronomical forcing and global topography. But these equations lack dissipation that (as inferred from astronomical observations) causes the Earth-Moon system to continuously loose rotational energy. The problem appeared to be resolved when G. I. Taylor recognised importance of the drag due to bottom friction in shallow seas. However, recent satellite measurements show that about one third of tidal energy is actually dissipated in the deep ocean near steep topographic features. This dissipation is attributed to generation of so-called internal tides, i.e internal waves at tidal frequency. And the latter are thought to play a crucial role in setting the global oceanic circulation, and, therefore, climate on Earth.

This discovery led to a surge of interest in simulations of global tides that can account for production of internal waves. Here, a new numerical model is presented that achieves this via a modal decomposition in the vertical of the Boussinesq equations. The model resolution is sufficiently high to resolve the first 3-4 internal wave modes, enough capture the majority of energy conversion from surface to internal tide. The advantages (and limitations) of our approach are examined, by comparison with the results obtained when internal tide drag is parametrized.

This talk is part of the Applied Mathematics Seminar Series series.

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• Applied Mathematics Seminar Series
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