Subtropical Contribution to Sub-Antarctic Mode Waters

Castro, Bieito Fernandez, Mazloff, Matthew, Williams, Richard G ORCID: 0000-0002-3180-7558 and Garabato, Alberto C Naveira (2022) Subtropical Contribution to Sub-Antarctic Mode Waters. GEOPHYSICAL RESEARCH LETTERS, 49 (11).

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Official URL: http://dx.doi.org/10.1029/2021gl097560

Abstract

<jats:title>Abstract</jats:title><jats:p>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<jats:sup>−2</jats:sup> y<jats:sup>−1</jats:sup>). 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.</jats:p>

Item Type:	Article
Uncontrolled Keywords:	Sub-Antartic Mode Water, Southern Ocean, biogeochemical Argo float, mixed layer, preformed nutrients, subtropical gyre
Divisions:	Faculty of Science and Engineering > School of Environmental Sciences
Depositing User:	Symplectic Admin
Date Deposited:	09 Sep 2022 15:06
Last Modified:	04 Sep 2023 02:43
DOI:	10.1029/2021GL097560
Open Access URL:	https://agupubs.onlinelibrary.wiley.com/doi/10.102...
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3164044