Shoaling of the off-equatorial south Indian Ocean thermocline: Is it driven by anthropogenic forcing?
Article first published online: 27 JUN 2008
Copyright 2008 by the American Geophysical Union.
Geophysical Research Letters
Volume 35, Issue 12, June 2008
How to Cite
2008), Shoaling of the off-equatorial south Indian Ocean thermocline: Is it driven by anthropogenic forcing? Geophys. Res. Lett., 35, L12711, doi:10.1029/2008GL034174., , and (
- Issue published online: 27 JUN 2008
- Article first published online: 27 JUN 2008
- Manuscript Accepted: 27 MAY 2008
- Manuscript Revised: 14 MAY 2008
- Manuscript Received: 31 MAR 2008
- thermocline shoaling;
- climate change
 Surface warming since 1950 in the off-equatorial south Indian Ocean (IO) occurs without a consistent surface heat flux trend, and is accompanied by a shoaling thermocline. The associated dynamics have not been fully explored. Using 20th century climate model experiments, we test if the shoaling thermocline is attributable to a transmission from the Pacific, where a similar shoaling occurs, and whether it is climate change-induced. A 22-model average produces no such signal. An average of a subset of models that better simulate El Niño-Southern Oscillation (ENSO) and its transmission produces the right direction of the IO thermocline trends. The shoaling in this subset average, taken as anthropogenically induced, is far weaker than the observed, suggesting a significant multidecadal variability component in the observed changes. The Pacific contribution increases with a stronger model ENSO amplitude and broader meridional structure, highlighting the importance of realistic ENSO simulations in modelling long-term change in the IO.