Will the Historic Southeasterly Wind over the Equatorial Pacific in March 2022 Trigger a Third-year La Nina Event?

Based on the updates of the Climate Prediction Center and International Research Institute for Climate and Society (CPC/IRI) and the China Multi-Model Ensemble (CMME) El Nino-Southern Oscillation (ENSO) Outlook issued in April 2022, La Nina is favored to continue through the boreal summer and fall, indicating a high possibility of a three-year La Nina (2020-23). It would be the first three-year La Nina since the 1998-2001 event, which is the only observed three-year La Nina event since 1980. By examining the status of air-sea fields over the tropical Pacific in March 2022, it can be seen that while the thermocline depths were near average, the southeasterly wind stress was at its strongest since 1980. Here, based on a quaternary linear regression model that includes various relevant air-sea variables over the equatorial Pacific in March, we argue that the historic southeasterly winds over the equatorial Pacific are favorable for the emergence of the third-year La Nina, and both the anomalous easterly and southerly wind stress components are important and contribute similar to 50% of the third-year La Nina growth, respectively. Additionally, the possible global climate impacts of this event are discussed.

Automated summary

Based on the latest climate predictions, it is expected that El Nino will continue into the summer and fall, leading to a possible three-year La Nina event. This would be the first three-year La Nina event since 1998-2001, and it could have significant global climate impacts.