Key Points about ENSO and its Phases
- ENSO (El Niño Southern Oscillation): ENSO is a significant climate phenomenon that involves changes in sea-surface temperatures (SST) in the central and eastern tropical Pacific Ocean. It affects various global weather patterns, including wind behavior, atmospheric pressure, and rainfall distribution.
- El Niño: Warmer-than-usual sea surface temperatures, associated with unusual global warming patterns.
- La Niña: Cooler-than-usual sea surface temperatures, often linked with colder atmospheric patterns and stronger trade winds.
- ENSO-Neutral: Neither El Niño nor La Niña dominates the climate system, making forecasts less certain, but often acting as a transitional phase between the two extreme conditions.
ENSO-Neutral Phase
- The ENSO-neutral phase is typically seen as a transition period between El Niño and La Niña.
- In March 2025, NOAA scientists observed that SST anomalies in the Niño-3.4 region had reached -0.01°C, much warmer than the La Niña threshold of -0.5°C.
- The cool waters that had characterized La Niña in previous months have now faded.
- Despite the presence of some La Niña-like atmospheric conditions (like strong trade winds), the lack of cool SSTs has led to the declaration of ENSO-neutral conditions.
- Temperature and Atmospheric Changes: The shift to neutral conditions occurred as warm waters spread westward across the eastern Pacific. Simultaneously, the pool of cool water beneath the surface began to shrink.
- Although signs of La Niña (like strong trade winds) persisted for a short time, the absence of cold surface waters meant the system no longer met the criteria to be classified as La Niña.
