Recent wind-driven change in Subantarctic Mode Water and its impact on ocean heat storage
journal contribution
posted on 2023-05-20, 02:26authored byGao, 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)