Near Surface Kinetic Energy Dissipation and its Relationship to Wavenumber-Directional Properties of Waves
Abstract
It is now established that turbulent kinetic energy dissipation rates near the surface are strongly enhanced over "law-of-the-wall" shear layer estimates in conditions of breaking waves. The long term goal of this work is to obtain a parametric description of the vertical structure of kinetic energy dissipation in the near surface zone beneath both breaking and non-breaking waves. The governing parameters include wind forcing, buoyancy flux, depth and wave properties, viz: wave age, wave height and steepness, and degree of wave breaking. Models of the ocean mixed layer have not typically taken the enhanced dissipation into account. Such a parameterization provides ocean modelers with an important boundary condition in coupled atmospheric-oceanic models. A second objective of this work is to determine the effects of sea state on air-sea fluxes. Recent results have shown that the drag coefficient decreases strongly with wave age, and also that the presence of swells affects the wind stress direction, and results in increased scatter in the magnitude of wind stress. Here, we look at quantifying the effect of swell (its wave age, direction and energy relative to the wind sea) on the stress magnitude, with the goal of explaining some of the high variability typical of field results, especially at lower wind speeds.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1998
- Accession Number
- ADA540087
Entities
People
- Mark A. Donelan
- William M. Drennan
Organizations
- Rosenstiel School of Marine, Atmospheric, and Earth Science