Subtropical contribution to sub‐Antarctic mode waters
Subtropical contribution to sub‐Antarctic mode waters
Sub-Antarctic Mode Waters (SAMW) form to the north of the Antarctic Circumpolar Current (ACC) through deep winter mixing. SAMW connect the atmosphere with the oceanic pycnocline, transferring heat and carbon into the ocean interior and supplying nutrients to the northern ocean basins. The processes controlling SAMW ventilation and properties remain poorly understood. Here, we investigate the significance and origin of a ubiquitous feature of SAMW formation regions: The seasonal build-up of a subsurface salinity maximum. With biogeochemical Argo floats, we show that this feature influences SAMW mixed-layer dynamics, and that its formation is associated with a decline in preformed nutrients comparable to biological drawdown in surface waters (∼0.15 mol m−2 y−1). Our analysis reveals that these features are driven by advection of warm, salty, nutrient-poor waters of subtropical origin along the ACC. This influx represents a leading-order term in the SAMW physical and biogeochemical budgets, and can impact large-scale nutrient distributions.
Southern Ocean, Sub-Antartic Mode Water, biogeochemical Argo float, mixed layer, preformed nutrients, subtropical gyre
Fernández Castro, Bieito
8017e93c-d5ee-4bba-b443-9c72ca512d61
Mazloff, Matthew
420716bf-9145-441a-b600-0233215ed6c6
Williams, Richard G.
2155309e-1c07-4365-b46a-04baeb2fb63c
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
16 June 2022
Fernández Castro, Bieito
8017e93c-d5ee-4bba-b443-9c72ca512d61
Mazloff, Matthew
420716bf-9145-441a-b600-0233215ed6c6
Williams, Richard G.
2155309e-1c07-4365-b46a-04baeb2fb63c
Naveira Garabato, Alberto C.
97c0e923-f076-4b38-b89b-938e11cea7a6
Fernández Castro, Bieito, Mazloff, Matthew, Williams, Richard G. and Naveira Garabato, Alberto C.
(2022)
Subtropical contribution to sub‐Antarctic mode waters.
Geophysical Research Letters, 49 (11), [e2021GL097560].
(doi:10.1029/2021GL097560).
Abstract
Sub-Antarctic Mode Waters (SAMW) form to the north of the Antarctic Circumpolar Current (ACC) through deep winter mixing. SAMW connect the atmosphere with the oceanic pycnocline, transferring heat and carbon into the ocean interior and supplying nutrients to the northern ocean basins. The processes controlling SAMW ventilation and properties remain poorly understood. Here, we investigate the significance and origin of a ubiquitous feature of SAMW formation regions: The seasonal build-up of a subsurface salinity maximum. With biogeochemical Argo floats, we show that this feature influences SAMW mixed-layer dynamics, and that its formation is associated with a decline in preformed nutrients comparable to biological drawdown in surface waters (∼0.15 mol m−2 y−1). Our analysis reveals that these features are driven by advection of warm, salty, nutrient-poor waters of subtropical origin along the ACC. This influx represents a leading-order term in the SAMW physical and biogeochemical budgets, and can impact large-scale nutrient distributions.
Text
Geophysical Research Letters - 2022 - Fern ndez Castro - Subtropical Contribution to Sub‐Antarctic Mode Waters
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Accepted/In Press date: 20 May 2022
e-pub ahead of print date: 27 May 2022
Published date: 16 June 2022
Additional Information:
Funding Information:
This research was funded by European Union's Horizon 2,020 research and innovation program under the Marie Skłodowska‐Curie grant agreement No. 834330 (SO‐CUP) to BFC. RGW was supported by NERC Grant No. NE/T010657/1. Float data were collected and made freely available by the Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) Project funded by the National Science Foundation, Division of Polar Programs (NSF PLR‐1425989, with extension NSF OPP‐1936222), supplemented by NASA, and by the International Argo Program and the NOAA programs that contribute to it.
Publisher Copyright:
© 2022. The Authors.
Keywords:
Southern Ocean, Sub-Antartic Mode Water, biogeochemical Argo float, mixed layer, preformed nutrients, subtropical gyre
Identifiers
Local EPrints ID: 458190
URI: http://eprints.soton.ac.uk/id/eprint/458190
ISSN: 0094-8276
PURE UUID: 563de21d-32aa-4423-8a04-005c423ce0c0
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Date deposited: 30 Jun 2022 16:43
Last modified: 17 Mar 2024 04:04
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Author:
Matthew Mazloff
Author:
Richard G. Williams
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