A zonally averaged, three-basin ocean circulation model for climate studies

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Climate Dynamics

DOI:https://doi.org/10.1007/s003820050051· OSTI ID:443825

Hovine, S; Fichefet, T ^[1]

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1. Universite Catholique de Louvain, Louvain-la-Neuve (Belgium)

A two-dimensional, three-basin ocean model suitable for long-term climate studies is developed. The model is based on the zonally averaged form of the primitive equations written in spherical coordinates. The east-west density difference which arises upon averaging the momentum equations is taken to be proportional to the meridional density gradient. Lateral exchanges of heat and salt between the basins are explicitly resolved. Moreover, the model includes bottom topography and has representations of the Arctic Ocean and of the Weddell and Ross seas. Under realistic restoring boundary conditions, the model reproduces the global conveyor belt: deep water is formed in the Atlantic between 60 and 70{degree}N at a rate of about 17 Sv (1 Sv=10{sup 6} m{sup 3}S{sup {minus}1}) and in the vicinity of the Antarctic continent, while the Indian and Pacific basins show broad upwelling. Superimposed on this thermohaline circulation are vigorous wind-driven cells in the upper thermocline. The simulated temperature and salinity fields and the computed meridional heat transport compare reasonably well with the observational estimates. When mixed boundary conditions i.e., a restoring condition no sea-surface temperature and flux condition on sea-surface salinity are applied, the model exhibits an irregular behavior before reaching a steady state characterized by self-sustained oscillations of 8.5-y period. The conveyor-belt circulation always results at this stage. A series of perturbation experiments illustrates the ability of the model to reproduce different steady-state circulations under mixed boundary conditions. Finally, the model sensitivity to various factors is examined. This sensitivity study reveals that the bottom topography and the presence of a submarine meridional ridge in the zone of the Drake passage play a crucial role in determining the properties of the model bottom-water masses. The importance of the seasonality of the surface forcing is also stressed.

• OSTI ID: 443825
• Journal Information: Climate Dynamics, Journal Name: Climate Dynamics Journal Issue: 6-7 Vol. 10; ISSN 0930-7575; ISSN CLDYEM
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ANTARCTIC OCEAN
ARCTIC OCEAN
CLIMATES
GLOBAL ASPECTS
MATHEMATICAL MODELS