Ocean Energetics, Tidal Conversion and Baroclinic Instability

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

Investigators

Abstract

Ocean energetics, tidal conversion and baroclinic instability William Young Scripps Institute of Oceanography The project is directed at understanding ocean energetics, mixing, baroclinic instability, tidal conversion, and the formation of the thermocline. The first part of the project is understanding the ramifications and extensions of constraints on the ocean energetics. Because there are no deep sources of buoyancy in the ocean (apart from small geothermal heating), one can show that in a statistically steady state there is no exchange between the reservoirs of kinetic and potential energy at every depth. The viscous dissipation of kinetic energy is balanced totally by tidal and wind forcing; there is essentially no net transformation o f potential into kinetic energy in the ocean. Theory will be developed and directed at analyzing Boussinesq energetics and the balances of available and background potential energies in the ocean. A second goal will be use primitive equation simulations and theory to examine the role of baroclinic eddies in forming the ocean thermocline. This will test the hypothesis that buoyancy flux associated with breaking internal gravity waves is balanced by baroclinic eddies. An extension of the quasi-geostrophic approximation, in which the background stratification is self-consistently determined, rather than simply prescribed, will also be developed and implemented numerically. The third goal will be an improved calculation of the generation of the internal tide by realistically large topography in an ocean with strongly variable buoyancy frequency. A new boundary-integral representation of the solution leads to an integral equation that enables efficient calculation of the internal gravity waves generated by topography. These goals relate to establishing the critical role of ocean mixing and turbulence in determining long-term changes in the Earth's climate via physical arguments based on energy balances.