The ocean's gravitational potential energy budget in a coupled climate model

• Published in: Geophysical research letters Vol. 40; no. 20; pp. 5417 - 5422
• Main Authors: Butler, E. D., Oliver, K. I., Gregory, J. M., Tailleux, R.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 28-10-2013; John Wiley & Sons, Inc
• Subjects: Adiabatic flow; adiabatic process; Adiabatic processes; available gravitational potential energy; Budgeting; Buoyancy; Circulation; Climate models; diabatic process; energy budget; Geophysics; gravitational potential energy; Gravity; Kinetic energy; Marine; Meteorology; ocean circulation; Oceanography; Oceans; Potential energy; Sustaining
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2013GL057996

This study examines, in a unified fashion, the budgets of ocean gravitational potential energy (GPE) and available gravitational potential energy (AGPE) in the control simulation of the coupled atmosphere‐ocean general circulation model HadCM3. Only AGPE can be converted into kinetic energy by adiabatic processes. Diapycnal mixing supplies GPE but not AGPE, whereas the reverse is true of the combined effect of surface buoyancy forcing and convection. Mixing and buoyancy forcing thus play complementary roles in sustaining the large‐scale circulation. However, the largest globally integrated source of GPE is resolved advection (+0.57 TW) and the largest sink is through parameterized eddy transports (−0.82 TW). The effect of these adiabatic processes on AGPE is identical to their effect on GPE, except for perturbations to both budgets due to numerical leakage exacerbated by nonlinearities in the equation of state.
Key Points
The ocean's (available) gravitational potential energy (GPE) budget is presented
The (available) GPE budget is dominated by adiabatic processes
Diapycnal mixing supplies GPE, made available by buoyancy forcing