Numerical Simulations and an Updated Parameterization of the Breaking Internal Solitary Wave Over the Continental Shelf

Abstract

AbstractThe breaking of internal solitary waves (ISWs) over slope‐shelf topography induces energy dissipation and enhances mixing. In this work, high‐resolution, laboratory‐scale simulations are employed to investigate the instability mechanisms and dissipation of ISWs. We find that the increasing nonhydrostatic pressure during deformation contributes to an adverse pressure gradient, which induces plunging flow for overturning. Shear instability and convective instabilities trigger wave breaking. Wave‐induced vortexes induce strong shearing and enhance the dissipation of energy by 1–2 orders of magnitude larger than that which occurs under stable conditions. Furthermore, based on laboratory results, we evaluate two commonly used parameterizations (Pacanowski & Philander, 1981, https://doi.org/10.1175/1520-0485(1981)011<1443:povmin>2.0.co;2, i.e., PP81; Klymak & Legg, 2010, https://doi.org/10.1016/j.ocemod.2010.02.005, i.e., KL10) in coarser‐resolution global ocean models by modifying the horizontal resolution from 100 grids every wavelength to approximately 30. The results show that PP81 and KL10 can both improve the estimation of the energy loss, but can only depict strong shear within the pycnocline and bottom boundary regions, respectively. Finally, an updated parameterization is presented that can effectively describe the strong shear in two regions during wave breaking. The flow field and dissipation are more consistent with the laboratory results using the new parameterization. This study improves the understanding of the mixing parameterizations in simulating the continuous processes of strong internal wave breaking.