Open AccessDynamical Potential Energy: A New Approach to Ocean Energetics
Author(s) -
Fabien Roquet
Publication year - 2013
Publication title -
journal of physical oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.706
H-Index - 143
eISSN - 1520-0485
pISSN - 0022-3670
DOI - 10.1175/jpo-d-12-098.1
Subject(s) - kinetic energy , potential energy , hydrostatic equilibrium , marine energy , energetics , buoyancy , geophysical fluid dynamics , mechanical energy , conservation of energy , energy transformation , ocean dynamics , mechanics , physics , ocean current , energy (signal processing) , geology , classical mechanics , power (physics) , thermodynamics , quantum mechanics , climatology
The concept of available potential energy is supposed to indicate which part of the potential energy is available to transform into kinetic energy. Yet it is impossible to obtain a unique definition of available potential energy for the real ocean because of nonlinearities of the equation of state, rendering its usefulness largely hypothetical. In this paper, the conservation of energy is first reformulated in terms of horizontal anomalies of density and pressure for a simplified ocean model using the Boussinesq and hydrostatic approximations. This framework introduces the concept of “dynamical potential energy,” defined as the horizontal anomaly of potential energy, to replace available potential energy. Modified conservation equations are derived that make it much simpler to identify oceanic power input by buoyancy and mechanical forces. Closed budgets of energy are presented for idealized circulations obtained with a general circulation model, comparing spatial patterns of power inputs generated by wind and thermal forcings. Finally, a generalization of the framework to compressible fluids is presented, opening the way to applications in atmosphere energetics.