Mechanical power input from buoyancy and wind to the circulation in an ocean model
Date
2012
Authors
Saenz Umana, Juan
Hogg, Andrew
Hughes, Graham
Griffiths, Ross
Journal Title
Journal ISSN
Volume Title
Publisher
American Geophysical Union
Abstract
We make a systematic quantitative comparison of the effects that surface buoyancy forcing and wind stress have on the energy balance of an idealized, rotating, pole-to-pole ocean model with a zonally re-entrant channel in the south, forced by realistic heat (buoyancy) fluxes and wind stresses representative of global climatology. Surface buoyancy fluxes and wind stress forcing are varied independently; both have significant effects on the reservoirs of various forms of energy and the rates of transfer between them. Importantly, we show for the first time that in the ocean, each power input has a positive feedback on the other. Changes in the rate of generation of available potential energy by buoyancy fluxes at the surface lead to similar changes in the rate of conversion of potential energy to kinetic energy by buoyancy forces (sinking) in the interior, and to changes in the rate of generation of kinetic energy by wind stress. Conversely, changes in the rate of generation of kinetic energy by wind stress lead to changes in the rate of generation of available potential energy by buoyancy forcing. We discuss how this feedback is mediated by the circumpolar current, and processes involving buoyancy, mixing and geostrophic balances. Our results support the notion that surface buoyancy forcing, along with wind and tidal forcing, plays an active role in the energy balance of the oceans. The overturning circulation in the oceans is not the result of a single driving force. Rather, it is a manifestation of a complex and subtle balance.
Description
Keywords
Keywords: Buoyancy fluxes; Buoyancy forces; Buoyancy forcing; Driving forces; Geostrophic balance; Global climatology; Mechanical power; Ocean model; Overturning circulation; Power input; Quantitative comparison; Surface buoyancy flux; Tidal forcing; Climatology; E
Citation
Collections
Source
Geophysical Research Letters
Type
Journal article
Book Title
Entity type
Access Statement
Open Access