Research reveals an important connection between westerly wind bursts and El Niño development

El Niño is a climatic phenomenon characterized by warming sea surface temperatures in the central and eastern equatorial Pacific Oceans, and is known to cause extreme weather events around the world, from droughts and floods to agriculture and ecosystem disruptions. Despite its global influence, the mechanisms behind El Niño are complex and not fully understood, making accurate predictions difficult.

A study published in Advances in Atmospheric Sciences revealed a key link between the western burst (WWBS) in the equatorial Pacific Ocean in the western central region and the westerly wind disruption (SUDDEN disruption) with sea surface temperature anomalies (SSTA). These findings provide new insights into how El Nino events develop, particularly at different stages of the El Nino Southern Oscillation (ENSO) cycle.

A team led by Professor Wenjun Zhang analyzed the behavior of WWB during two El Niño events using a reanalysis dataset and climate modelling. Cycle (transition from La Niña to El Niño) and acyclic (transition from normal conditions to El Niño).

This study found that WWB is more frequent in the West Central Equatorial Pacific during the developmental spring of noncirculating El Nino events, consistent with local warming of sea surface temperatures. In contrast, WWBS is not active until summer with cyclical El Nino events.

The study also revealed that WWB generation is closely linked to deep atmospheric convection promoted by the SSTA, the basis of the equatorial Pacific Ocean in the central atmosphere. Even if there is little temperature change in this area, the high background sea surface temperature can cause an atmospheric reaction. During an aperiodic El Niño event, Spring SSTs strengthen WWB in spring, while colder SSTs associated with La Niña suppress WWB in cyclical events.

“Our findings show that WWBS appears to be non-random, but is closely related to sea surface temperature conditions in the central western,” said Professor Wenjun Chan, corresponding author of the study. “This understanding is an important step in improving El Niño’s forecasts.”

This study highlights the irregular nature of El Niño events that do not always follow a predictable cycle. By clarifying the relationship between WWB and SSTAS, this study provides a more clear context for the processes that promote El Niño development. This knowledge will help improve forecasting and help the community better prepare for the impacts of El Niño-related extreme weather.

The findings also point to the need for further research into the processes that cause abnormal warming in the West Central Pacific, which could serve as an early indicator of El Niño. Understanding whether these temperature changes are directly linked to ENSO dynamics or influenced by other factors can improve prediction accuracy.