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Internal Tide Scattering by an Isolated Cyclogeostrophic Vortex

Internal tides (ITs) are internal waves which oscillate at the tidal frequencies. ITs may cross entire ocean basins and along the way, they may be redirected, break, and dissipate. The fate of ITs are largely determined by their interaction with energetic balanced vortical flows which are ubiquitous in the ocean. Mesoscale wave-vortex interactions are characterized by low Rossby numbers. With the aid of satellite altimetry, the effects of mesoscale eddies on ITs has been used successfully to map low mode IT propagation. In the submesoscale, these interactions become more complex, due to strong non-linearities, a partial breakdown of geostrophic balance, and intermediate scales for both balanced flows and ITs, which are hard to observe with current methods. However, the next generation of satellite altimetry, the Surface Water and Ocean Topography mission, will have fine enough resolution to begin to capture the submesoscale, which makes it an exciting time to explore wave-vortex interactions in this regime. We use the one-layer shallow water model to run idealized numerical simulations of a single wave mode propagating through a (cyclo)geostrophic vortex. We have conducted a parameter sweep across a variety of dynamical regimes to observe the IT energy redistribution at the lee side of a submesoscale vortex. We find that the transfer of energy to the principle scattered wave is proportional to the Rossby number, the ratio of length scales between vortex length and incoming wavelength, and inversely proportional to the Burger number.

Event series  Brewer-Wilson Seminar Series