Song et al. (2026) Why does El Niño develop slowly but decay rapidly

Identification

• Journal: npj Climate and Atmospheric Science
• Year: 2026
• Date: 2026-08-05
• Authors: Xiaomeng Song, Renhe Zhang, Xinyao Rong, Jingzhi Su
• DOI: 10.1038/s41612-026-01498-2

Research Groups

• State Key Laboratory of Severe Weather Meteorological Science and Technology，CEMC, Beijing, China
• CMA Earth System Modeling and Prediction Centre (CEMC), Beijing, China
• Key Laboratory of Earth System Modeling and Prediction, China Meteorological Administration, Beijing, China
• Department of Atmospheric and Oceanic Sciences/Institute of Atmospheric Sciences, Fudan University, Shanghai, China

Short Summary

This study investigates the phase asymmetry between El Niño development and decay phases. The authors develop a mixed-layer heat budget framework to diagnose the thermodynamic and dynamical contributions to this asymmetry.

Objective

• To understand the mechanisms driving the temporal asymmetry of El Niño events
• To quantify the relative contributions of thermodynamic damping, zonal advection, and thermocline feedbacks to the decay phase

Study Configuration

• Spatial Scale: Global, with a focus on the Pacific Ocean and the Niño3.4 region
• Temporal Scale: Interannual, with a focus on El Niño events from 1950 to 2015

Methodology and Data

• Models used: Reanalysis datasets (SODA2.2.4, SODA3.4.2, GODAS, ORAS4)
• Data sources: Satellite, observation, reanalysis data

Main Results

• The study finds that thermodynamic damping, zonal advection, and thermocline feedbacks contribute to the decay phase of El Niño events.
• The surface heat flux term is the primary negative contributor to the temperature-tendency asymmetry.
• Zonal advective feedback and thermocline feedback jointly provide the main negative contribution.

Contributions

• This study provides a new framework for diagnosing ENSO temporal asymmetry and identifying potential precursors that may inform El Niño prediction systems.
• The results highlight the importance of accounting for vertical sensitivity in heat budget attribution.

Funding

• State Key Laboratory of Severe Weather Meteorological Science and Technology, China Meteorological Administration
• National Natural Science Foundation of China (Grant Nos. 41675043 and 41975045)
• Shanghai Municipal Education Commission (Grant No. 2017QM027)

Citation

@article{Song2026Why,
  author = {Song, Xiaomeng and Zhang, Renhe and Rong, Xinyao and Su, Jingzhi},
  title = {Why does El Niño develop slowly but decay rapidly},
  journal = {npj Climate and Atmospheric Science},
  year = {2026},
  doi = {10.1038/s41612-026-01498-2},
  url = {https://doi.org/10.1038/s41612-026-01498-2}
}