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Wind-driven processes controlling oceanic heat delivery to the Amundsen Sea, Antarctica

Wind-driven processes controlling oceanic heat delivery to the Amundsen Sea, Antarctica
Wind-driven processes controlling oceanic heat delivery to the Amundsen Sea, Antarctica
Variability in the heat delivery by Circumpolar Deep Water (CDW) is responsible for modulating the basal melting of the Amundsen Sea ice shelves. However, the mechanisms controlling the CDW inflow to the region’s continental shelf remain little understood. Here, a high-resolution regional model is used to assess the processes governing heat delivery to the Amundsen Sea. The key mechanisms are identified by decomposing CDW temperature variability into two components associated with 1) changes in the depth of isopycnals [heave (HVE)], and 2) changes in the temperature of isopycnals [water mass property changes (WMP)]. In the Dotson–Getz trough, CDW temperature variability is primarily associated with WMP. The deeper thermocline and shallower shelf break hinder CDW access to that trough, and CDW inflow is regulated by the uplift of isopycnals at the shelf break—which is itself controlled by wind-driven variations in the speed of an undercurrent flowing eastward along the continental slope. In contrast, CDW temperature variability in the Pine Island–Thwaites trough is mainly linked to HVE. The shallower thermocline and deeper shelf break there permit CDW to persistently access the continental shelf. CDW temperature in the area responds to wind-driven modulation of the water mass on-shelf volume by changes in the rate of inflow across the shelf break and in Ekman pumping-induced vertical displacement of isopycnals within the shelf. The western and eastern Amundsen Sea thus represent distinct regimes, in which wind forcing governs CDW-mediated heat delivery via different dynamics.
0022-3670
2829-2849
Dotto, Tiago S.
437639c6-9c67-4c83-ace3-bb490a2f44d7
Naveira Garabato, Alberto C.
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Bacon, Sheldon
1e7aa6e3-4fb4-4230-8ba7-90837304a9a7
Holland, Paul R.
1288654c-2b5b-4d4c-b360-7eebe59c7539
Kimura, Satoshi
c2d72821-b5a4-4407-95f8-d2204e771007
Firing, Yvonne L.
2518c141-9864-4b97-a9ed-adbab90dca66
Tsamados, Michel
c206a0fe-e2c2-4853-9d71-4d3d9c882af5
Wåhlin, Anna K.
d7379b0f-2ec8-4547-8d22-4e1f6b295fd7
Jenkins, Adrian
a36e1c51-a60a-465a-b1c4-e39ff3344b03
Dotto, Tiago S.
437639c6-9c67-4c83-ace3-bb490a2f44d7
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Bacon, Sheldon
1e7aa6e3-4fb4-4230-8ba7-90837304a9a7
Holland, Paul R.
1288654c-2b5b-4d4c-b360-7eebe59c7539
Kimura, Satoshi
c2d72821-b5a4-4407-95f8-d2204e771007
Firing, Yvonne L.
2518c141-9864-4b97-a9ed-adbab90dca66
Tsamados, Michel
c206a0fe-e2c2-4853-9d71-4d3d9c882af5
Wåhlin, Anna K.
d7379b0f-2ec8-4547-8d22-4e1f6b295fd7
Jenkins, Adrian
a36e1c51-a60a-465a-b1c4-e39ff3344b03

Dotto, Tiago S., Naveira Garabato, Alberto C., Bacon, Sheldon, Holland, Paul R., Kimura, Satoshi, Firing, Yvonne L., Tsamados, Michel, Wåhlin, Anna K. and Jenkins, Adrian (2019) Wind-driven processes controlling oceanic heat delivery to the Amundsen Sea, Antarctica. Journal of Physical Oceanography, 49 (11), 2829-2849. (doi:10.1175/JPO-D-19-0064.1).

Record type: Article

Abstract

Variability in the heat delivery by Circumpolar Deep Water (CDW) is responsible for modulating the basal melting of the Amundsen Sea ice shelves. However, the mechanisms controlling the CDW inflow to the region’s continental shelf remain little understood. Here, a high-resolution regional model is used to assess the processes governing heat delivery to the Amundsen Sea. The key mechanisms are identified by decomposing CDW temperature variability into two components associated with 1) changes in the depth of isopycnals [heave (HVE)], and 2) changes in the temperature of isopycnals [water mass property changes (WMP)]. In the Dotson–Getz trough, CDW temperature variability is primarily associated with WMP. The deeper thermocline and shallower shelf break hinder CDW access to that trough, and CDW inflow is regulated by the uplift of isopycnals at the shelf break—which is itself controlled by wind-driven variations in the speed of an undercurrent flowing eastward along the continental slope. In contrast, CDW temperature variability in the Pine Island–Thwaites trough is mainly linked to HVE. The shallower thermocline and deeper shelf break there permit CDW to persistently access the continental shelf. CDW temperature in the area responds to wind-driven modulation of the water mass on-shelf volume by changes in the rate of inflow across the shelf break and in Ekman pumping-induced vertical displacement of isopycnals within the shelf. The western and eastern Amundsen Sea thus represent distinct regimes, in which wind forcing governs CDW-mediated heat delivery via different dynamics.

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e-pub ahead of print date: 25 October 2019
Published date: November 2019
Additional Information: © Copyright 2019 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a website or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. All AMS journals and monograph publications are registered with the Copyright Clearance Center (http://www.copyright.com). Questions about permission to use materials for which AMS holds the copyright can also be directed to permissions@ametsoc.org. Additional details are provided in the AMS Copyright Policy statement, available on the AMS website (http://www.ametsoc.org/CopyrightInformation).

Identifiers

Local EPrints ID: 435901
URI: http://eprints.soton.ac.uk/id/eprint/435901
ISSN: 0022-3670
PURE UUID: 6cae2067-e07b-411b-be5e-ff0e05db52af

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Date deposited: 22 Nov 2019 17:30
Last modified: 26 Nov 2021 07:14

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Contributors

Author: Tiago S. Dotto
Author: Sheldon Bacon
Author: Paul R. Holland
Author: Satoshi Kimura
Author: Yvonne L. Firing
Author: Michel Tsamados
Author: Anna K. Wåhlin
Author: Adrian Jenkins

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