University Of Tasmania

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Nutrient variability in Subantarctic Mode Waters forced by the Southern Annular Mode and ENSO

journal contribution
posted on 2023-05-17, 22:52 authored by Ayers, JM, Peter StruttonPeter Strutton
As the primary source of nutrients to the global thermocline, Subantarctic Mode Waters (SAMWs) play a key role in primary production and climate. Here we use repeat hydrographic World Ocean Circulation Experiment/Climate Variability and Predictability data to quantify interannual SAMW nutrient variability and its forcing. Pacific sector SAMW nutrients were significantly correlated with the Southern Annular Mode (SAM) and wind stress curl anomalies associated with a faster meridional overturning circulation (MOC). A stronger MOC results in greater upwelling of nutrients at high latitudes, increased Ekman transport of nutrients equatorward, and subduction of higher preformed nutrient loads in SAMWs. Australian sector SAMWs were significantly correlated with El Niño-Southern Oscillation (ENSO), likely due to its modulation of transport in the East Australian Current extension. Interannual variability in SAMW nutrients impacts downstream tropical export production by as much as 5-12% of the annual mean. Key Points Subantarctic Mode Water nutrients vary interannually by 15-50% of the mean Wind-driven circulation forces 40-65% of Pacific sector nutrient variability Nutrient variability impacts downstream production and carbon drawdown ©2013. American Geophysical Union. All Rights Reserved.


Publication title

Geophysical Research Letters










Institute for Marine and Antarctic Studies


Amer Geophysical Union

Place of publication

2000 Florida Ave Nw, Washington, USA, Dc, 20009

Rights statement

Copyright 2013 American Geophysical Union

Repository Status

  • Restricted

Socio-economic Objectives

Atmospheric composition (incl. greenhouse gas inventory)

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