Antarctic Intermediate Water Mass Formation in Ocean General Circulation Models

Sørensen, Jacob Viborg Tornfeldt; Ribbe, Joachim; Shaffer, Gary

doi:10.1175/1520-0485(2001)031<3295:aiwmfi>2.0.co;2

Cited by 27 publications

(25 citation statements)

References 26 publications

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“…The simulated ocean circulation agrees with OGCM simu- lations with similar resolutions (e.g., England 1993;Sørensen et al 2001;Stammer et al 2002); for example, the intensity of the overturning in the Atlantic associated with NADW formation is ϳ18 Sv and the global AABW overturning is ϳ10 Sv, with ϳ3 Sv in the Atlantic. A detailed validation was presented in Iudicone (2007) and was summarized in IMBS08.…”

Section: The Main Transformations In the Global Overturning In The Modelsupporting

confidence: 60%

The Global Conveyor Belt from a Southern Ocean Perspective

Iudicone

Speich

Madec

et al. 2008

Journal of Physical Oceanography

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Recent studies have proposed the Southern Ocean as the site of large water-mass transformations; other studies propose that this basin is among the main drivers for North Atlantic Deep Water (NADW) circulation. A modeling contribution toward understanding the role of this basin in the global thermohaline circulation can thus be of interest. In particular, key pathways and transformations associated with the thermohaline circulation in the Southern Ocean of an ice-ocean coupled model have been identified here through the extensive use of quantitative Lagrangian diagnostics. The model Southern Ocean is characterized by a shallow overturning circulation transforming 20 Sv (1 Sv ϵ 10 6 m 3 s Ϫ1 ) of thermocline waters into mode waters and a deep overturning related to the formation of Antarctic Bottom Water. Mode and intermediate waters contribute to 80% of the upper branch of the overturning in the Atlantic Ocean north of 30°S. A net upwelling of 11.5 Sv of Circumpolar Deep Waters is simulated in the Southern Ocean. Antarctic Bottom Water upwells into deep layers in the Pacific basin, forming Circumpolar Deep Water and subsurface thermocline water. The Southern Ocean is a powerful consumer of NADW: about 40% of NADW net export was found to upwell in the Southern Ocean, and 40% is transformed into Antarctic Bottom Water. The upwelling occurs south of the Polar Front and mainly in the Indian and Pacific Ocean sectors. The transformation of NADW to lighter water occurs in two steps: vertical mixing at the base of the mixed layer first decreases the salinity of the deep water upwelling south of the Antarctic Circumpolar Current, followed by heat input by air-sea and diffusive fluxes to complete the transformation to mode and intermediate waters.

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Section: The Main Transformations In the Global Overturning In The Modelsupporting

confidence: 60%

The Global Conveyor Belt from a Southern Ocean Perspective

Iudicone

Speich

Madec

et al. 2008

Journal of Physical Oceanography

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“…The model has 31 vertical levels and a horizontal resolution of 2°cos(latitude) except in the equatorial regions, leading to a resolution of approximately 1°in the Southern Ocean. Although the model is not eddy permitting, it represents a substantial improvement in resolution relative to previous modeling studies of the AAIW in the South Pacific (e.g., Sørensen et al 2001;Saenko et al 2003). After 1500 years of spinup (without acceleration), the model has reached an equilibrium state.…”

Section: A Model Descriptionmentioning

confidence: 97%

An Exchange Window for the Injection of Antarctic Intermediate Water into the South Pacific

Iudicone

Rodgers

Schopp

et al. 2007

Journal of Physical Oceanography

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Antarctic Intermediate Water (AAIW) occupies the intermediate horizon of most of the world oceans. Formed in the Southern Ocean, it is characterized by a relative salinity minimum. With a new, denser in situ National Oceanographic Data Center dataset, the authors have reanalyzed the export characteristics of AAIW from the Southern Ocean into the South Pacific Ocean. These new data show that part of the AAIW is exported from the subpolar frontal region by the large-scale circulation through an exchange window of 10°width situated east of 90°W in the southeast corner of the Pacific basin. This suggests the origin of this water to be in the Antarctic Circumpolar Current. A set of numerical modeling experiments has been used to reproduce these observed features and to demonstrate that the dynamics of the exchange window is controlled by the basin-scale meridional pressure gradient. The exchange of AAIW between the Southern and Pacific Oceans must therefore be understood in the context of the large basin-scale dynamical balance rather than simply local effects.

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“…Possible changes in South Atlantic water mass formation will be analyzed using simulations from the Community Climate System Model version 3 (CCSM3). The justification is that SAMW and AAIW are simulated much better in the ocean components of climate models used in the IPCC fourth assessment report than in previous reports, see Sorensen et al [2001, Figure 2], for example. Very recently, Sloyan and Kamenkovich [2007] have made a detailed study of the SAMW and AAIW simulation in eight of the climate models used in the IPCC fourth assessment report.…”

Section: Introductionmentioning

confidence: 98%

Changes in subduction in the South Atlantic Ocean during the 21st century in the CCSM3

Góes

Wainer

Gent

et al. 2008

Geophysical Research Letters

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The Community Climate System Model version 3 is used to analyse changes in water mass subduction rates in the South Atlantic Ocean over the 21st century. The model results are first compared to observations over 1950–2000, and shown to be rather good. The subduction rates do not change significantly over the 21st century, but the densities at which water masses form become significantly lighter. The strong westerly winds in this region do not change much, which suggests small changes to the rate at which the Atlantic sector of the Southern Ocean takes up heat and carbon dioxide over the 21st century.

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Antarctic Intermediate Water Mass Formation in Ocean General Circulation Models

Cited by 27 publications

References 26 publications

The Global Conveyor Belt from a Southern Ocean Perspective

The Global Conveyor Belt from a Southern Ocean Perspective

An Exchange Window for the Injection of Antarctic Intermediate Water into the South Pacific

Changes in subduction in the South Atlantic Ocean during the 21st century in the CCSM3

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