Emerging Skill in Multi-Year Prediction of the Indian Ocean Dipole

F Feba,Satish R Shetye,Karumuri Ashok,Matthew Collins

doi:10.3389/fclim.2021.736759

F Feba, Satish R Shetye + Show 2 more

Open Access

https://doi.org/10.3389/fclim.2021.736759

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Abstract

The Indian Ocean Dipole is a leading phenomenon of climate variability in the tropics, which affects the global climate. However, the best lead prediction skill for the Indian Ocean Dipole, until recently, has been limited to ~6 months before the occurrence of the event. Here, we show that multi-year prediction has made considerable advancement such that, for the first time, two general circulation models have significant prediction skills for the Indian Ocean Dipole for at least 2 years after initialization. This skill is present despite ENSO having a lead prediction skill of only 1 year. Our analysis of observed/reanalyzed ocean datasets shows that the source of this multi-year predictability lies in sub-surface signals that propagate from the Southern Ocean into the Indian Ocean. Prediction skill for a prominent climate driver like the Indian Ocean Dipole has wide-ranging benefits for climate science and society.

Highlights

The Indian Ocean Dipole (IOD) is an inter-annual coupled ocean–atmosphere phenomenon in the tropical Indian Ocean that peaks during the boreal fall season (September to November; SON)
In addition to its own coupled dynamics (Gualdi et al, 2003; Yamagata et al, 2004; Behera et al, 2006; Ha et al, 2017; Tanizaki et al, 2017; Saji, 2018; Marathe et al, 2021), the IOD is suggested to be triggered by other inter-annual processes such as the El Niño–Southern Oscillation (ENSO), the dominant climate driver from the tropics
While the lead prediction skills of the Indian Ocean Dipole Mode Index (IODMI) from the CanCM4 fall below 95% confidence level at 4–5-year leads, these skill levels are still significant at a 90% confidence level

Summary

Introduction

The Indian Ocean Dipole (IOD) is an inter-annual coupled ocean–atmosphere phenomenon in the tropical Indian Ocean that peaks during the boreal fall season (September to November; SON). In addition to its own coupled dynamics (Gualdi et al, 2003; Yamagata et al, 2004; Behera et al, 2006; Ha et al, 2017; Tanizaki et al, 2017; Saji, 2018; Marathe et al, 2021), the IOD is suggested to be triggered by other inter-annual processes such as the El Niño–Southern Oscillation (ENSO), the dominant climate driver from the tropics

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