Multiscale turbulent eddies in topographic wakes: a LES study
Abstract
Ocean currents impinge on three-dimensional topographic features such as islands and seamounts to engender turbulent wakes with cohe,rent eddies and broadband turbulence. The multiscale variability in the wake of an obstacle is a product of turbulent bottom bound,ary layers on inclined slopes, coherent vortices shed from the obstacle, as well as barotropic and baroclinic instabilities of the,wake. We propose high-resolution, large eddy simulations (LES) to conduct a process study of wake dynamics which, unlike prior work,in oceanic wakes, will resolve turbulence. These high-resolution non-hydrostatic simulations enable quantification of turbulent diss,ipation, mixing, and drag as a function of topographic Rossby and Froude number. A newly developed hybrid approach will be utilized, to efficiently evolve near-wake turbulent vortices to the larger space and time scales of the intermediate and far wake. Both a uni,form current and a vertically sheared current with lateral variability of density will be considered. The spatio-temporal structure,of the wake will be examined using a variety of diagnostics including energy and momentum budgets, modal analysis and Lagrangian t,racers. We anticipate that the simulation results will be useful to constrain topographic drag and turbulence parameterizations in l,arge-scale ocean models as well as to interpret field observations during FLEAT and ARCTREX.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 10, 2021
- Source ID
- N000142212024
Entities
People
- Sutanu Sarkar
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego