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Water mass exchange in the Southern Ocean in coupled climate models


Downes, S and Gnanadesikan, A and Griffies, SM and Sarmiento, JL, Water mass exchange in the Southern Ocean in coupled climate models, Journal of Physical Oceanography, 41, (9) pp. 1756-1771. ISSN 0022-3670 (2011) [Refereed Article]

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DOI: doi:10.1175/2011JPO4586.1


The authors estimate water mass transformation rates resulting from surface buoyancy fluxes and interior diapycnal fluxes in the region south of 308S in the Estimating the Circulation and Climate of the Ocean (ECCO) model-based state estimation and three free-running coupled climate models. The meridional transport of deep and intermediate waters across 308S agrees well between models and observationally based estimates in the Atlantic Ocean but not in the Indian and Pacific, where the model-based estimates are much smaller. Associated with this, in the models about half the southward-flowing deep water is converted into lighter waters and half is converted to denser bottom waters, whereas the observationally based estimates convert most of the inflowing deep water to bottom waters. In the models, both Antarctic Intermediate Water (AAIW) and Antarctic Bottom Water (AABW) are formed primarily via an interior diapycnal transformation rather than being transformed at the surface via heat or freshwater fluxes. Given the small vertical diffusivity specified in the models in this region, the authors conclude that other processes such as cabbeling and thermobaricity must be playing an important role in water mass transformation. Finally, in the models, the largest contribution of the surface buoyancy fluxes in the Southern Ocean is to convert Upper Circumpolar Deep Water (UCDW) and AAIW into lighter Subantarctic Mode Water (SAMW).

Item Details

Item Type:Refereed Article
Keywords:water mass transformation
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Physical oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Climate change models
UTAS Author:Downes, S (Dr Stephanie Downes)
ID Code:103126
Year Published:2011
Web of Science® Times Cited:40
Deposited By:CRC-Antarctic Climate & Ecosystems
Deposited On:2015-09-22
Last Modified:2017-11-01

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