Evolution of IOD-ENSO relationship at multiple time scales
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Both El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are important indicators of the potential impact of climate at the global scale. The IOD-ENSO relationship at different timescales is temporally non-uniform, which is important to understand in order to evaluate its socioeconomic impacts. Here, we developed and applied a wavelet cross-correlation analysis approach for investigating the evolution of the IOD-ENSO relationship over a 150-year period. We found that the IOD-ENSO relationship was statistically significant at the dominant timescales of 1.5, 3, and 24 year, with the correlation degree varying with time. The hysteresis effect between IOD and ENSO and the evolution of their relationship obviously differ at the three dominant timescales. The positive (negative) IOD and El Niño (La Niña) events were mainly determined by the variability of IOD and ENSO at the timescale < 3 year. Strong positive IOD events in the September-October-November period would more likely be related to El Niño events 2 months later and La Niña events 14 months later, but negative IOD events would rarely co-occur with El Niño or La Niña events. The result achieved in this study can serve as a useful guide for the long-term forecast of IOD and ENSO.
KeywordsCorrelation analysis Wavelet analysis Detection and attribution El Niño-Southern Oscillation Indian Ocean dipole Climate change
The authors gratefully acknowledge the valuable comments and suggestions given by the Editor and the anonymous reviewers. The authors also thank the National Center for Atmospheric Research, Computational and Information Systems Laboratory, for sharing the HadISST data used for this study.
This project was financially supported by the National Key Research and Development Program (No. 2017YFA0603702), the National Natural Science Foundation of China (No. 91647110, 41776023), the Program for the “Bingwei” Excellent Talents from the Institute of Geographic Sciences and Natural Resources Research, CAS, and the Youth Innovation Promotion Association CAS (No. 2017074).
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