Fernandes et al. (2026) Is the ENSO modulation of MJO and its impacts on South American summer rainfall simulated in model experiments?

Identification

• Journal: Journal of Climate
• Year: 2026
• Date: 2026-10-06
• Authors: Laís Gonçalves Fernandes, Alice M. Grimm
• DOI: 10.1175/jcli-d-25-0475.1

Research Groups

• Department of Meteorology, University of Reading, United Kingdom
• Postgraduate Program in Water Resources and Environmental Engineering, Federal University of Paraná (UFPR), Brazil
• Department of Physics, Federal University of Paraná (UFPR), Brazil
• Department of Oceanography, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil

Short Summary

This study investigates the impact of El Niño-Southern Oscillation (ENSO) on the Madden-Julian Oscillation (MJO) and its effects on South American summer rainfall using model experiments. The results show that ENSO influences MJO characteristics and teleconnections to South America.

Objective

• Investigate the role of ENSO in modulating MJO and its impacts on South American summer rainfall.
• Assess whether ENSO affects MJO convection, eastward propagation, and teleconnections to South America.

Study Configuration

• Spatial Scale: Global scale with a focus on South America and the central-east subtropical South Pacific (CSSP) region.
• Temporal Scale: 60-year long simulations with different spatial resolutions.

Methodology and Data

• Models used: UK Met Office Unified Model Global Ocean Mixed Layer configuration (MetUM-GOML3).
• Data sources: Model output data from experiments with and without ENSO cycles.

Main Results

• Simulations without ENSO show an extratropical teleconnection triggered by enhanced convection in the CSSP region, with strongest impact on central-east South American precipitation in MJO phase 8.
• ENSO affects the basic state and MJO convection, modulating teleconnections to South America in simulations with ENSO cycles.
• EN (LN) strengthens (weakens) the MJO eastward propagation and convection, but both EN and LN produce enhanced convection over the CSSP region in phase 8.

Contributions

• This study provides new insights into the nonlinear effects of ENSO on MJO anomalies over South America, highlighting the importance of considering ENSO states when studying MJO impacts.
• The results demonstrate that ENSO influences MJO characteristics and teleconnections to South America, indicating a complex relationship between these climate phenomena.

Funding

• This research was funded by [insert funding agency/project codes/reference numbers].

Citation

@article{Fernandes2026Is,
  author = {Fernandes, Laís Gonçalves and Grimm, Alice M.},
  title = {Is the ENSO modulation of MJO and its impacts on South American summer rainfall simulated in model experiments?},
  journal = {Journal of Climate},
  year = {2026},
  doi = {10.1175/jcli-d-25-0475.1},
  url = {https://doi.org/10.1175/jcli-d-25-0475.1}
}