Random Ocean Swell-Rays: A Stochastic Framework

Originating from distant storms, swell systems radiate across all ocean basins. Far from their sources, emerging surface waves have low steepness characteristics, with very slow amplitude variations. Swell propagation then closely follows principles of geometrical optics, i.e. the eikonal approximation to the wave equation, with a constant wave period along geodesics, when following a wave packet at its group velocity. The phase averaged evolution of quasi-linear wave fields is then dominated by interactions with underlying current and/or topography changes. Comparable to the propagation of light in a slowly varying medium, over many wavelengths, cumulative effects can lead to refraction, i.e. change of the direction of propagation of a given wave packet, so that it departs from its initial ray-propagation direction. This opens the possibility of using surface swell systems as probes to estimate turbulence along their propagating path.

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Resseguier Valentin, Hascoët Erwan, Chapron Bertrand (2023). Random Ocean Swell-Rays: A Stochastic Framework. In Chapron Bertrand, Crisan Dan, Holm Darryl, Mémin Etienne, Radomska Anna (Eds.) (2023). Stochastic Transport in Upper Ocean Dynamics. STUOD 2021 Workshop, London, UK, September 20-23. Springer International Publishing. ISBN 978-3-031-18987-6. Part of the Mathematics of Planet Earth book series (MPE,volume 10), pp.259-271. Springer International Publishing. https://doi.org/10.1007/978-3-031-18988-3_16, https://archimer.ifremer.fr/doc/00813/92470/

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