A study by the University of Hyderabad (UoH) in collaboration with the University of Exeter, for the first time, has discovered that there are decadal prediction skills for the Indian Ocean Dipole (IOD)

Climate scientists have been trying to forecast various climate processes with a few years lead. The newly emerging field of decadal prediction is all about forecasting the climate for the next 5-20 years, helping stakeholders in decision-making and strategising.

A joint team of researchers analysed retrospective decadal forecasts, with initial conditions from 1960 to 2011, from four models, generated by the scientific community under the Coupled Model Intercomparison Project (version 5) decadal prediction project. “The authors found our that IOD has a longer prediction skill on a multi-year scale. They find that two models, MIROC5 from Japan, and CanCM4 from Canada, can predict 10 years in advance,while providing strongest leads up to 2 years,” UoH said in a release.

The study also indicates that the subsurface ocean signals in the Southern Ocean provides cues for predicting the IOD.

The El Niño-Southern Oscillation (ENSO) events, which occur in the tropical pacific, are considered to be a major climate driver.

The Indian Ocean Dipole (IOD) is another important climate driver that affects the global climate. The positive phase of the IOD is characterised by above normal sea surface temperature in the equatorial eastern Indian Ocean, and below normal temperatures in the western equatorial Indian Ocean.

The negative IOD events are characterised by the opposite signature. Strong positive IOD events which occurred in years such as 2019, 2007, 1997,1994, 1967 1963 and 1961 were associated with strong rains along the Indian monsoon trough region. “The latest extreme positive IOD occurred in summer of 2019, and contributed to the unprecedented wildfire in Australia, floods in East Africa and above normal rainfall and floods in India,’’ the release said.

Strong positive IOD events have impacts on Indian summer monsoon that are opposite to both canonical and Modoki El Niños; the latter which cause below normal rainfall in India. The monsoon seasons of 1997 and 1994 were such typical examples, as per the findings of the study.

The research was carried out by K Ashok, his PhD student Feba Francis, and Satish Shetye, a former Chair Professor of Centre for Earth, Ocean and Atmospheric Sciences, University of Hyderabad. The UoH team collaborated with Mat Collins of the University of Exeter in the research.

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