Huang et al. (2025) Modulation of ENSO on the MJO Forecast

Identification

• Journal: Atmospheric Research
• Year: 2025
• Date: 2025-10-08
• Authors: Yi Huang, Yuntao Wei, Hong‐Li Ren
• DOI: 10.1016/j.atmosres.2025.108510

Research Groups

• Department of Atmospheric and Oceanic Sciences and Institute of Atmosphere Sciences, Shanghai and Frontiers Sciences Center of Atmosphere-Ocean Interaction, CMA-FDU Joint Laboratory of Marine Meteorology, Key Laboratory of Polar Atmosphere-ocean-ice System for Weather and Climate, Ministry of Education, Fudan University, Shanghai, China
• State Key Laboratory of Severe Weather Meteorological Science and Technology, Chinese Academy of Meteorological Sciences, Beijing, China

Short Summary

This study systematically evaluates the influence of El Niño-Southern Oscillation (ENSO) on Madden-Julian Oscillation (MJO) forecast skill across seasons, initial phases, and amplitudes using multiple dynamical models, revealing distinct seasonal dependencies where La Niña enhances MJO predictability in boreal winter and El Niño improves it in boreal summer.

Objective

• To systematically evaluate how El Niño-Southern Oscillation (ENSO) modulates Madden-Julian Oscillation (MJO) forecast skill across different seasons, initial phases, and amplitudes using multiple dynamical models.

Study Configuration

• Spatial Scale: Global tropics, with specific focus on the Maritime Continent and central-eastern Pacific.
• Temporal Scale: Subseasonal-to-seasonal (S2S) forecasts, covering boreal winter and boreal summer, and MJO oscillations with periods of 20 to 100 days (forecast horizons of two weeks to two months).

Methodology and Data

• Models used: Multiple dynamical models, including operational dynamical S2S models.
• Data sources: Real-time multivariate MJO (RMM) index for MJO characterization and forecast verification.

Main Results

• MJO forecast skill exhibits distinct seasonal dependencies on ENSO.
• In boreal winter, MJO forecasts are more skillful during La Niña, primarily due to improved prediction of the more intense phase-2 MJO. During El Niño, phase-2 MJO propagates too fast and encounters an exaggerated Maritime Continent barrier, reducing accuracy.
• Superior prediction of initially strong MJO events during La Niña further boosts boreal winter forecast skill.
• In boreal summer, El Niño yields better MJO forecasts than La Niña, as models accurately capture the eastward-propagating, wavenumber-1 MJO structure in phases 3–4 under El Niño conditions.
• During La Niña summers, westward-propagating disturbances dominate in MJO phases 3–4, which models consistently fail to reproduce, thus lowering forecast skill.
• In La Niña summers, forecast skill declines with increasing MJO amplitude, especially when initialized from phases 1–3, as models struggle with continuous eastward propagation of high-amplitude MJO due to exaggerated dry, westward-moving signals from the central-eastern Pacific.

Contributions

• Enhances understanding of MJO–ENSO interaction dynamics, particularly addressing the inadequately examined relationship in boreal summer.
• Provides a systematic evaluation of MJO forecast skill dependence on ENSO across seasons, initial phases, and amplitudes.
• Offers practical implications for improving subseasonal forecasting by identifying conditions under which MJO predictability is enhanced or reduced.

Funding

• Not specified in the provided text.

Citation

@article{Huang2025Modulation,
  author = {Huang, Yi and Wei, Yuntao and Ren, Hong‐Li},
  title = {Modulation of ENSO on the MJO Forecast},
  journal = {Atmospheric Research},
  year = {2025},
  doi = {10.1016/j.atmosres.2025.108510},
  url = {https://doi.org/10.1016/j.atmosres.2025.108510}
}