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Recent wind-driven change in Subantarctic Mode Water and its impact on ocean heat storage

journal contribution
posted on 2023-05-20, 02:26 authored by Gao, L, Stephen Rintoul, Yu, W
The subduction and export of Subantarctic Mode Water (SAMW) supplies the upper limb of the overturning circulation and makes an important contribution to global heat, freshwater, carbon and nutrient budgets. Upper ocean heat content has increased since 2006, helping to explain the so-called global warming hiatus between 1998 and 2014, with much of the ocean warming concentrated in extratropical latitudes of the Southern Hemisphere in close association with SAMW and Antarctic Intermediate Water (AAIW)6,7. Here we use Argo observations to assess changes in the thickness, depth and heat content of the SAMW layer. Between 2005 and 2015, SAMW has thickened (3.6 ± 0.3 m yr−1), deepened (2.4 ± 0.2 m yr−1) and warmed (3.9 ± 0.3 W m−2). Wind forcing, rather than buoyancy forcing, is largely responsible for the observed trends in SAMW. Most (84%) of the increase in SAMW heat content is the result of changes in thickness; warming by buoyancy forcing (increased heat flux to the ocean) accounts for the remaining 16%. Projected increases in wind stress curl would drive further deepening of SAMW and increase in heat storage in the Southern Hemisphere oceans.

History

Publication title

Nature Climate Change

Volume

8

Pagination

58-63

ISSN

1758-678X

Department/School

Institute for Marine and Antarctic Studies

Publisher

Nature Publishing Group

Place of publication

United Kingdom

Rights statement

Copyright 2017 Macmillan Publishers Limited, part of Springer Nature

Repository Status

  • Restricted

Socio-economic Objectives

Effects of climate change on Antarctic and sub-Antarctic environments (excl. social impacts)

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