Late 20th century Indian Ocean heat content gain masked by wind forcing

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Date
2020-10-26
Authors
Ummenhofer, Caroline C.
Ryan, Svenja
England, Matthew H.
Scheinert, Markus
Wagner, Patrick
Biastoch, Arne
Böning, Claus W.
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10.1029/2020GL088692
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Keywords
Decadal variability
Hiatus
Indian Ocean
Ocean heat content
Ocean models
Pacific Ocean
Abstract
Rapid increases in upper 700‐m Indian Ocean heat content (IOHC) since the 2000s have focused attention on its role during the recent global surface warming hiatus. Here, we use ocean model simulations to assess distinct multidecadal IOHC variations since the 1960s and explore the relative contributions from wind stress and buoyancy forcing regionally and with depth. Multidecadal wind forcing counteracted IOHC increases due to buoyancy forcing from the 1960s to the 1990s. Wind and buoyancy forcing contribute positively since the mid‐2000s, accounting for the drastic IOHC change. Distinct timing and structure of upper ocean temperature changes in the eastern and western Indian Ocean are linked to the pathway how multidecadal wind forcing associated with the Interdecadal Pacific Oscillation is transmitted and affects IOHC through local and remote winds. Progressive shoaling of the equatorial thermocline—of importance for low‐frequency variations in Indian Ocean Dipole occurrence—appears to be dominated by multidecadal variations in wind forcing.
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Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 47(22), (2020): e2020GL088692, doi:10.1029/2020GL088692.
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Ummenhofer, C. C., Ryan, S., England, M. H., Scheinert, M., Wagner, P., Biastoch, A., & Boening, C. W. (2020). Late 20th century Indian Ocean heat content gain masked by wind forcing. Geophysical Research Letters, 47(22), e2020GL088692.
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