Breakdown of wind-wave equilibrium and scaling surface turbulence in the Norwegian Sea
Abstract
Accurate modelling predictions for the evolution of the ocean surface and subsequent ambient noise generation are crucial for Navy operations. As models are coarse in time and space, robust parameterizations are required for the air-sea momentum and heat fluxes, as well as the dissipation of heat and energy. These processes, which ultimately control the state of the surface ocean, are strongly modulated by the surface gravity wave field. Surface waves evolve according to the balance between wind-energy flux to the wave field, non-linear transfers in energy between waves of different frequencies, and dissipation of energy through wave breaking. Most forecast models assume a state of equilibrium between the wind and waves, where wind energy input to the wind-sea portion of the wave spectrum is locally balanced by wave-breaking dissipation. However, this equilibrium is expected to breakdown during rapid changes in forcing and in the presence of strong surface gradients, causing forecast models to fail. Both are characteristic of the Norwegian Sea, with frequent storms and strong surface fronts generated at the intersection of different water masses. In a recent ONR DRI, #Northern Ocean Rapid Surface Evolution# (NORSE), near-surface turbulence, acoustic, wave and surface flux data were collected with a fleet of Lagrangian surface drifters during three field campaigns in 2021-2023. The work proposed herein is to analyze the drifterdata to determine the parameter dependence of departure from equilibrium, and to characterize the ocean surface during non-equilibrium conditions. The analysis will hinge on accurate estimation of the near-surface turbulent kinetic energy dissipation rate and wind-energy flux leveraging recent methodological advances by the PI. The comprehensive dataset collected during the NORSE campaign, namely near-surface wind and turbulence combined with ambient noise, provides a unique opportunity to explore their interdependence.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142412569
Entities
People
- Kristin Zeiden
Organizations
- Office of Naval Research
- United States Navy
- University of Washington