Abstract
Recently, it has been shown for the first time by observations that an anticyclonic mesoscale eddy can generate internal waves (wavelengths of 0.4 to 1 km) that carry energy away from the eddy. In the present study, we investigate a possible mechanism for generating internal waves near the edge of a submesoscale eddy. The study was motivated by airborne infrared imagery that shows curved thermal bands (wavelengths ∼70 m) near the edge of a 1-km-diameter cyclonic eddy. We hypothesize that these bands represent internal wave wakes generated by turbulent perturbations having scales of a few tens of meters that are advected along the eddy’s thermal perimeter. An analytical theory is developed to investigate this for an idealized perturbation advected by a circular current. Calculations show that, for a reasonable choice of parameter values, an internal wave wake develops around the eddy that has spiral-like phase lines resembling the orientations and wavelengths of the field observations. The general validity of our proposed mechanism should be verified with further studies.
Acknowledgements
We thank J. C. McWilliams and R. Barkan for helpful discussions, and R. Davy for editorial comments.
Disclosure statement
No potential conflict of interest was reported by the authors.