NSFGEO-NERC: Transfer of energy from the ocean mesoscale to the internal wave field by stimulated loss of balance

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

The ocean energy budget is not well understood and there is uncertainty in the content of and fluxes between ocean energy reservoirs. Internal waves, which result from wind, tides and topographic interactions, are present throughout the ocean and contain about 10% of the ocean energy budget while the remaining 90% is associated with mesoscale eddies. In order to reach steady-state, the same amount of energy entering the system must leave the system; however, the method of removal is not clear. This group of researchers has recently obtained results that suggest a transfer of energy from the mesoscale flow to near-inertial waves. This loss of energy is also known as the stimulated loss of balance (SLOB), which influences mesoscale flow. This project seeks to quantify the impact of ocean internal waves on mesoscale flow as well as determine if internal tides also act as a source of energy transfer. The researchers plan to utilize theory and numerical simulations to investigate the role of internal waves in the mesoscale energy budget. The knowledge gained from this proposal will enhance understanding of internal waves, which can be used to advance climate models. A better understanding of internal tides will likely lead to more accurate interpretations of satellite altimeter data as well. Two postdoctoral research assistants will benefit from state-of-the-art physical oceanography and applied mathematics training through this project. This project supports an international collaboration between Scripps Institute of Oceanography and the University of Edinburgh. The resulting models and model output will be made available to other researchers for teaching and learning purposes. Recent results produced by this group of researchers show that the advection and refraction of near-inertial waves by mesoscale flow is necessarily accompanied by a transfer of energy from the mesoscale flow to the inertial waves. Theoretical and numerical analyses will be used to develop a model that couples internal wave dynamics with that of balanced mesoscale flow to understand energy transfers from the mesoscale reservoir to internal waves via SLOB. The specific objectives of this project are to: assess and develop the hypothesis that SLOB plays a major role in the mesoscale energy budget, and to investigate SLOB by components of the internal wave spectrum, particularly the internal tide. The proposed methodology will also aid in the development and assessment of techniques with broad applicability to multi-scale problems involving the scattering and transformation of waves by turbulent flows. As a result of this project, a quantitative understanding of the role played by SLOB in the ocean energy budget will be obtained.