New study reveals key linkages between westerly wind bursts and El Niño development

El Niño, a climate phenomenon marked by warming sea surface temperatures in the central and eastern equatorial Pacific, is known to trigger extreme weather events worldwide, from droughts and floods to disruptions in agriculture and ecosystems. Despite its global impact, the mechanisms behind El Niño remain complex and not fully understood, making accurate predictions challenging.

A study published in Advances in Atmospheric Sciences has uncovered important connections between Westerly Wind Bursts (WWBs)—sudden disruptions of the easterly trade winds—and sea surface temperature anomalies (SSTAs) in the western-central equatorial Pacific. These findings offer new insights into how El Niño events develop, particularly during different phases of the El Niño-Southern Oscillation (ENSO) cycle.

Led by Prof. Wenjun Zhang and his team, the research used reanalysis datasets and climate models to analyze the behavior of WWBs during two types of El Niño events: cyclic (transitioning from La Niña to El Niño) and noncyclic (transitioning from normal conditions to El Niño). The study found that WWBs are more frequent in the western-central equatorial Pacific during the spring of developing noncyclic El Niño events, coinciding with localized warming of sea surface temperatures. In contrast, WWBs do not become active until the summer in cyclic El Niño events.

The research also revealed that the occurrence of WWBs is closely tied to atmospheric deep convection, which is driven by underlying SSTAs in the western-central equatorial Pacific. Even small temperature changes in this region can trigger significant atmospheric responses due to its high background sea surface temperatures. During noncyclic El Niño events, warmer SSTs enhance WWBs in the spring, while colder SSTs associated with La Niña suppress WWBs in cyclic events.

“Our findings show that WWBs seem not random but are closely linked to sea surface temperature conditions in the western-central Pacific,” said Prof. Wenjun Zhang, the corresponding author of the study. “This understanding is a key step toward improving El Niño predictions.”

The study highlights the irregular nature of El Niño events, which do not always follow a predictable cycle. By clarifying the relationship between WWBs and SSTAs, the research provides a clearer picture of the processes driving El Niño development. This knowledge could help improve forecasts, allowing communities to better prepare for the impacts of El Niño-related extreme weather.

The findings also point to the need for further research into the processes causing anomalous warming in the western-central Pacific, which may serve as an early indicator of El Niño. Understanding whether these temperature changes are directly tied to ENSO dynamics or influenced by other factors could enhance prediction accuracy.