The cold transit of Southern Ocean upwelling
The cold transit of Southern Ocean upwelling
The upwelling of deep waters in the Southern Ocean is a critical component of the climate system. The time and zonal mean dynamics of this circulation describe the upwelling of Circumpolar Deep Water and the downwelling of Antarctic Intermediate Water. The thermodynamic drivers of the circulation and their seasonal cycle play a potentially key regulatory role. Here an observationally constrained ocean model and an observation‐based seasonal climatology are analyzed from a thermodynamic perspective, to assess the diabatic processes controlling overturning in the Southern Ocean. This reveals a seasonal two‐stage cold transit in the formation of intermediate water from upwelled deep water. First, relatively warm and saline deep water is transformed into colder and fresher near‐surface winter water via wintertime mixing. Second, winter water warms to form intermediate water through summertime surface heat fluxes. The mixing‐driven pathway from deep water to winter water follows mixing lines in thermohaline coordinates indicative of nonlinear processes.
Evans, Dafydd Gwyn
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Zika, Jan D.
1843cce7-77ce-4ef6-9f79-bcf4f9db30e5
Naveira Garabato, Alberto C.
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Nurser, A. J. George
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Evans, Dafydd Gwyn
4e1ed170-9119-4b35-a45f-55f8d07fa24e
Zika, Jan D.
1843cce7-77ce-4ef6-9f79-bcf4f9db30e5
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Nurser, A. J. George
2493ef9a-21e9-4d8b-9c32-08677e7e145a
Evans, Dafydd Gwyn, Zika, Jan D., Naveira Garabato, Alberto C. and Nurser, A. J. George
(2018)
The cold transit of Southern Ocean upwelling.
Geophysical Research Letters, 45 (24).
(doi:10.1029/2018GL079986).
Abstract
The upwelling of deep waters in the Southern Ocean is a critical component of the climate system. The time and zonal mean dynamics of this circulation describe the upwelling of Circumpolar Deep Water and the downwelling of Antarctic Intermediate Water. The thermodynamic drivers of the circulation and their seasonal cycle play a potentially key regulatory role. Here an observationally constrained ocean model and an observation‐based seasonal climatology are analyzed from a thermodynamic perspective, to assess the diabatic processes controlling overturning in the Southern Ocean. This reveals a seasonal two‐stage cold transit in the formation of intermediate water from upwelled deep water. First, relatively warm and saline deep water is transformed into colder and fresher near‐surface winter water via wintertime mixing. Second, winter water warms to form intermediate water through summertime surface heat fluxes. The mixing‐driven pathway from deep water to winter water follows mixing lines in thermohaline coordinates indicative of nonlinear processes.
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Evans_et_al_2018_Geophysical_Research_Letters_1_
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Accepted/In Press date: 2 December 2018
e-pub ahead of print date: 5 December 2018
Identifiers
Local EPrints ID: 427438
URI: http://eprints.soton.ac.uk/id/eprint/427438
ISSN: 0094-8276
PURE UUID: 6ceb2641-1342-440c-b3b1-c25281c40bee
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Date deposited: 16 Jan 2019 17:30
Last modified: 16 Mar 2024 07:29
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Author:
Dafydd Gwyn Evans
Author:
Jan D. Zika
Author:
A. J. George Nurser
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