Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Improved Predictability of the Indian Ocean Dipole Using Seasonally Modulated ENSO Forcing Forecasts

TitleImproved Predictability of the Indian Ocean Dipole Using Seasonally Modulated ENSO Forcing Forecasts
Publication TypeJournal Article
Year of Publication2019
JournalGeophysical Research Letters
Volume46
Number16
Pages9980-9990
Abstract / Summary

Despite recent progress in seasonal forecast systems, the predictive skill for the Indian Ocean Dipole (IOD) remains typically limited to a lead time of one season or less in both dynamical and empirical models. Here we develop a simple stochastic‐dynamical model (SDM) to predict the IOD using seasonally modulated El Niño–Southern Oscillation (ENSO) forcing together with a seasonally modulated Indian Ocean coupled ocean‐atmosphere feedback. The SDM, with either observed or forecasted ENSO forcing, exhibits generally higher skill and longer lead times for predicting IOD events than the operational Climate Forecast System version 2 and the Scale Interaction Experiment–Frontier system. The improvements mainly originate from better prediction of ENSO‐dependent IOD events and from reducing false alarms. These results affirm our hypothesis that operational IOD predictability beyond persistence is largely controlled by ENSO predictability and the signal‐to‐noise ratio of the system. Therefore, potential future ENSO improvements in models should translate to more skillful IOD predictions.

URLhttp://dx.doi.org/10.1029/2019gl084196
DOI10.1029/2019gl084196
Journal: Geophysical Research Letters
Year of Publication: 2019
Volume: 46
Number: 16
Pages: 9980-9990
Publication Date: 08/2019

Despite recent progress in seasonal forecast systems, the predictive skill for the Indian Ocean Dipole (IOD) remains typically limited to a lead time of one season or less in both dynamical and empirical models. Here we develop a simple stochastic‐dynamical model (SDM) to predict the IOD using seasonally modulated El Niño–Southern Oscillation (ENSO) forcing together with a seasonally modulated Indian Ocean coupled ocean‐atmosphere feedback. The SDM, with either observed or forecasted ENSO forcing, exhibits generally higher skill and longer lead times for predicting IOD events than the operational Climate Forecast System version 2 and the Scale Interaction Experiment–Frontier system. The improvements mainly originate from better prediction of ENSO‐dependent IOD events and from reducing false alarms. These results affirm our hypothesis that operational IOD predictability beyond persistence is largely controlled by ENSO predictability and the signal‐to‐noise ratio of the system. Therefore, potential future ENSO improvements in models should translate to more skillful IOD predictions.

DOI: 10.1029/2019gl084196
Citation:
Zhao, S, F Jin, and M Stuecker.  2019.  "Improved Predictability of the Indian Ocean Dipole Using Seasonally Modulated ENSO Forcing Forecasts."  Geophysical Research Letters 46(16): 9980-9990.  https://doi.org/10.1029/2019gl084196.