Reduction in Meridional Heat Export Contributes to Recent Indian Ocean Warming

K. McMonigal, Kathryn L. Gunn, Lisa M. Beal, Shane Elipot, Josh K. Willis

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Since 2000, the Indian Ocean has warmed more rapidly than the Atlantic or Pacific Oceans. Air–sea fluxes alone cannot explain the rapid Indian Ocean warming, which has so far been linked to an increase in temperature transport into the basin through the Indonesian Throughflow (ITF). Here, we investigate the role that the heat transport out of the basin at 36°S plays in the warming. Adding the heat transport out of the basin to the ITF temperature transport into the basin, we calculate the decadal mean Indian Ocean heat budget over the 2010s. We find that heat convergence increased within the Indian Ocean over 2000–19. The heat convergence over the 2010s is of the same order as the warming rate, and thus the net air–sea fluxes are near zero. This is a significant change from previous analyses using transbasin hydrographic sections from 1987, 2002, and 2009, which all found divergences of heat. A 2-yr time series shows that seasonal aliasing is not responsible for the decadal change. The anomalous ocean heat convergence over the 2010s in comparison with previous estimates is due to changes in ocean currents at both the southern boundary (33%) and the ITF (67%). We hypothe-size that the changes at the southern boundary are linked to an observed broadening of the Agulhas Current, implying that temperature and velocity data at the western boundary are crucial to constrain heat budget changes.

Original languageEnglish (US)
Pages (from-to)329-345
Number of pages17
JournalJournal of Physical Oceanography
Issue number3
StatePublished - Mar 2022
Externally publishedYes


  • In situ oceanic observations
  • Indian Ocean
  • Ocean circulation
  • Seasonal cycle
  • Trends

ASJC Scopus subject areas

  • Oceanography


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