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Diapycnal mixing in the Southern Ocean diagnosed using the DIMES Tracer and Realistic Velocity Fields

Diapycnal mixing in the Southern Ocean diagnosed using the DIMES Tracer and Realistic Velocity Fields
Diapycnal mixing in the Southern Ocean diagnosed using the DIMES Tracer and Realistic Velocity Fields
In this work, we use realistic isopycnal velocities with a 3‐D eddy diffusivity to advect and diffuse a tracer in the Antarctic Circumpolar Current, beginning in the Southeast Pacific and progressing through Drake Passage. We prescribe a diapycnal diffusivity which takes one value in the SE Pacific west of 67°W and another value in Drake Passage east of that longitude, and optimize the diffusivities using a cost function to give a best fit to experimental data from the DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) tracer, released near the boundary between the Upper and Lower Circumpolar Deep Water. We find that diapycnal diffusivity is enhanced 20‐fold in Drake Passage compared with the SE Pacific, consistent with previous estimates obtained using a simpler advection‐diffusion model with constant, but different, zonal velocities east and west of 67°W. Our result shows that diapycnal mixing in the ACC plays a significant role in transferring buoyancy within the Meridional Overturning Circulation.
2169-9275
2615-2634
Mackay, Neill
04a0ec32-fec9-4876-a0c3-509177721555
Ledwell, James R.
c369f91d-fa36-42dd-9391-910486f60c2d
Messias, Marie-josé
024b3503-8bfc-4e1d-aeeb-6c8ed0d6830b
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Brearley, J. Alexander
74993854-269c-4802-9b30-b3c34da8206d
Meijers, Andrew J.s.
747ecd45-cdbe-47be-b952-4b724096f9d5
Jones, Daniel C.
44fc07b3-5fb7-4bf5-9cec-78c78022613a
Watson, Andrew J.
55e619df-85a4-4079-922b-8cb1f17290a8
Mackay, Neill
04a0ec32-fec9-4876-a0c3-509177721555
Ledwell, James R.
c369f91d-fa36-42dd-9391-910486f60c2d
Messias, Marie-josé
024b3503-8bfc-4e1d-aeeb-6c8ed0d6830b
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Brearley, J. Alexander
74993854-269c-4802-9b30-b3c34da8206d
Meijers, Andrew J.s.
747ecd45-cdbe-47be-b952-4b724096f9d5
Jones, Daniel C.
44fc07b3-5fb7-4bf5-9cec-78c78022613a
Watson, Andrew J.
55e619df-85a4-4079-922b-8cb1f17290a8

Mackay, Neill, Ledwell, James R., Messias, Marie-josé, Naveira Garabato, Alberto C., Brearley, J. Alexander, Meijers, Andrew J.s., Jones, Daniel C. and Watson, Andrew J. (2018) Diapycnal mixing in the Southern Ocean diagnosed using the DIMES Tracer and Realistic Velocity Fields. Journal of Geophysical Research: Oceans, 123 (4), 2615-2634. (doi:10.1002/2017JC013536).

Record type: Article

Abstract

In this work, we use realistic isopycnal velocities with a 3‐D eddy diffusivity to advect and diffuse a tracer in the Antarctic Circumpolar Current, beginning in the Southeast Pacific and progressing through Drake Passage. We prescribe a diapycnal diffusivity which takes one value in the SE Pacific west of 67°W and another value in Drake Passage east of that longitude, and optimize the diffusivities using a cost function to give a best fit to experimental data from the DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) tracer, released near the boundary between the Upper and Lower Circumpolar Deep Water. We find that diapycnal diffusivity is enhanced 20‐fold in Drake Passage compared with the SE Pacific, consistent with previous estimates obtained using a simpler advection‐diffusion model with constant, but different, zonal velocities east and west of 67°W. Our result shows that diapycnal mixing in the ACC plays a significant role in transferring buoyancy within the Meridional Overturning Circulation.

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Accepted/In Press date: 20 March 2018
e-pub ahead of print date: 13 April 2018

Identifiers

Local EPrints ID: 421918
URI: http://eprints.soton.ac.uk/id/eprint/421918
ISSN: 2169-9275
PURE UUID: d0cc02ec-e581-4a35-89d1-5538ea6751d2

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Date deposited: 09 Jul 2018 16:30
Last modified: 08 Jan 2022 06:48

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Contributors

Author: Neill Mackay
Author: James R. Ledwell
Author: Marie-josé Messias
Author: J. Alexander Brearley
Author: Andrew J.s. Meijers
Author: Daniel C. Jones
Author: Andrew J. Watson

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