title: The role of the SST-thermocline relationship in Indian Ocean Dipole skewness and its response to global warming.
abstract: A positive Indian Ocean Dipole (IOD) tends to have stronger cold sea surface temperature anomalies (SSTAs) over the eastern Indian Ocean with greater impacts than warm SSTAs that occur during its negative phase. Two feedbacks have been suggested as the cause of positive IOD skewness, a positive Bjerknes feedback and a negative SST-cloud-radiation (SCR) feedback, but their relative importance is debated. Using inter-model statistics, we show that the most important process for IOD skewness is an asymmetry in the thermocline feedback, whereby SSTAs respond to thermocline depth anomalies more strongly during the positive phase than negative phase. This asymmetric thermocline feedback drives IOD skewness despite positive IODs receiving greater damping from the SCR feedback. In response to global warming, although the thermocline feedback strengthens, its asymmetry between positive and negative IODs weakens. This behaviour change explains the reduction in IOD skewness that many models display under global warming.
authors.affiliation: 1] CSIRO Marine and Atmospheric Research, Aspendale, Victoria, Australia [2] School of Earth Sciences, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Ng
authors.affiliation: CSIRO Marine and Atmospheric Research, Aspendale, Victoria, Australia.
authors.forename: Wenju
authors.initials: W
authors.lastname: Cai
authors.affiliation: School of Earth Sciences, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Walsh
references.citation: Nature. 1999 Sep 23;401(6751):356-60
references.pmid: 16862107
references.citation: Nature. 2010 Feb 11;463(7282):747-56
references.pmid: 20148028
references.citation: Nature. 1999 Sep 23;401(6751):360-3
references.pmid: 16862108
references.citation: Sci Rep. 2012;2:269
references.pmid: 22355781
references.citation: Nature. 2014 Jan 2;505(7481):37-42
references.pmid: 24380952