Tropical Indian Ocean and ENSO relationships in a changed climate

Shamal Marathe, Pascal Terray, Ashok Karumuri

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

We explore the current (1958–2005 period) and near future (2006–2050 period) teleconnections between El Niño Southern Oscillation (ENSO), Indian Ocean Basin Mode (IOBM), and Indian Ocean Dipole (IOD) as simulated in historical and Representative Concentration Pathway (RCP8.5) simulations of 32 coupled models that participated in the phase five of Coupled Model Intercomparison Project (CMIP5). A set of 16 CMIP5 models out of 32 models, which perform best to simulate tropical climate variability in recent decades, is first selected using a robust method based on the Empirical Orthogonal Function analysis for detailed analysis. Most of these models show modest capability in reproducing the seasonal cycle of ENSO types in the current period. Further, amplitude of Indian Ocean (IO) modes is overestimated by the 16 models along with large inter-model spread. Based on these results, a subset of 9 models is formed, which simulate a realistic seasonal phase-locking of ENSO for a robust assessment of future teleconnections. No significant change in El Niño amplitude is detected in near future. However, the IOBM is projected to be weaker during late spring and early summer. The IOD is projected to be stronger during boreal summer in the future relative to the current period. We also investigate if there are any changes from historical to RCP 8.5 simulations in the strength of the IO negative feedback on ENSO with a multiple linear regression approach. The IO negative feedback strengthens significantly in the RCP8.5 scenario due to the increasing role of IOBM in speeding the transition from El Niño to La Niña, despite its reduction of amplitude. In contrast, IOD loses its predictive value in the future projections.
Original languageEnglish (US)
Pages (from-to)3255-3276
Number of pages22
JournalClimate Dynamics
Volume56
Issue number9-10
DOIs
StatePublished - May 1 2021
Externally publishedYes

ASJC Scopus subject areas

  • Atmospheric Science

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