The Seasonal Cycle of the South Indian Ocean Subtropical Gyre Circulation as Revealed by Argo and Satellite Data

K. McMonigal, Lisa Beal, Josh K. Willis

Research output: Contribution to journalArticle

Abstract

The seasonal variability in volume transport of the South Indian Ocean subtropical gyre is characterized for the first time. Only three complete hydrographic crossings of the gyre have been conducted over a 22-year period, with an upcoming repeat in 2019. Changes to geostrophic transport and thermocline properties imply a strengthening of the gyre from 1987 to 2002. However, some of this strengthening could result from aliasing of seasonal variability. We use data from Argo, satellite altimetry, and an Agulhas Current transport proxy at 34S to quantify the seasonal variability of the upper 2,000-m volume transport. A semiannual cycle is revealed, with peak-to-peak amplitude of 6.4 ± 3.1 Sv(1Sv = 106 m3 s−1) and dominated by annual anomalies in quadrature near the eastern and western boundaries. Seasonal aliasing does not account for the observed gyre strengthening.

Original languageEnglish (US)
Pages (from-to)9034-9041
Number of pages8
JournalGeophysical Research Letters
Volume45
Issue number17
DOIs
StatePublished - Sep 16 2018

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Argo
Indian Ocean
gyre
satellite data
volume transport
cycles
satellite altimetry
thermoclines
quadratures
transport properties
thermocline
anomalies
anomaly

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

The Seasonal Cycle of the South Indian Ocean Subtropical Gyre Circulation as Revealed by Argo and Satellite Data. / McMonigal, K.; Beal, Lisa; Willis, Josh K.

In: Geophysical Research Letters, Vol. 45, No. 17, 16.09.2018, p. 9034-9041.

Research output: Contribution to journalArticle

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