Sea Ice‐Driven Variability in the Pacific Subantarctic Mode Water Formation Regions

Sanders, R.N.C. ORCID:; Meijers, A.J.S. ORCID:; Holland, P.R. ORCID:; Naveira Garabato, A.C.. 2023 Sea Ice‐Driven Variability in the Pacific Subantarctic Mode Water Formation Regions. Journal of Geophysical Research: Oceans, 128 (12), e2023JC020006. 22, pp.

Before downloading, please read NORA policies.
Text (Open Access)
© 2023. The Authors.
JGR Oceans - 2023 - Sanders - Sea Ice‐Driven Variability in the Pacific Subantarctic Mode Water Formation Regions.pdf - Published Version
Available under License Creative Commons Attribution 4.0.

Download (2MB) | Preview


Subantarctic Mode Water (SAMW) forms north of the Subantarctic Front, in regions of deep winter mixed layers, and is important to the absorption and storage of anthropogenic CO2 and heat. Two SAMW pools exist in the Pacific, a lighter Central mode (CPSAMW), and a denser Southeast mode (SEPSAMW). Both have experienced significant interannual variability in thickness and properties in recent years. We compute mixed layer temperature and salinity budgets for the two SAMW formation regions, to determine the relative contribution of processes driving variability in the properties of mixed layers that subduct to form SAMW. The dominant drivers of temperature and salinity variability are shown to be surface fluxes, horizontal advection, and entrainment of deeper water. Salt advection into each SAMW formation region is found to be strongly correlated with changes in sea ice area in the northern Ross Sea, with lags of up to 2 years. Further correlation is found between meridional salt advection in the southeast Pacific formation regions, and sea ice area in the northern Amundsen/Bellingshausen seas, suggesting that freshwater derived from sea ice melt reaches the SEPSAMW formation region within 6 months. In 2016, strong advective freshening of the SEPSAMW formation region, linked to increased winter sea ice in the Amundsen/Bellingshausen seas, led to anomalously fresh mixed layers. However, a regime change in Antarctic sea ice in 2016 resulted in a subsequent lack of the usual advective freshening in the SEPSAMW formation region, driving increased salinity of the mixed layer the following year.

Item Type: Publication - Article
Digital Object Identifier (DOI):
ISSN: 2169-9275
Date made live: 12 Dec 2023 12:21 +0 (UTC)

Actions (login required)

View Item View Item

Document Downloads

Downloads for past 30 days

Downloads per month over past year

More statistics for this item...