September 19th, 2024
El Niño, a notorious climate phenomenon characterised by the warming of the central equatorial Pacific Ocean, has officially been confirmed by the National Institute of Water and Atmospheric Research (NIWA) to have arrived this September, satisfying a majority of the institute's classification criteria.
According to NIWA, "The monthly NINO3.4 Index anomaly (in the central equatorial Pacific) at the end of September was +1.58˚C, within the range of a strong El Niño." Notably, such figures place this year's El Niño event as one of the strongest since records began in 1981, surpassed only by the events of 2015 and 1997.
The Southern Oscillation Index (SOI) has further reinforced this classification, coming in at a value of "-1.3 during September," fitting well within the recognised El Niño range.
Trade winds, which play a critical role in the development and sustenance of El Niño events, have exhibited intriguing patterns in the last two months.
In September, trade wind strength "was below normal in the west-central Pacific just east of the International Date Line and near normal or above normal farther east," a pattern akin to that observed in August. For October, NIWA anticipates a stronger indication for diminishing trades in the east-central Pacific, which would contribute to further warming in the Niño 3 and 3.4 regions.
The sub-surface conditions of the eastern equatorial Pacific Ocean have been drawing significant attention. As of late September, anomalies ranging between "+3˚C to +6˚C were occurring in the upper 100 metres in the east." Such figures, coupled with the consistent distribution of this anomalously warm water, align perfectly with "the development of an east-based canonical El Niño event."
NIWA's projections for the coming months show a continuation of this warming trend, forecasting that these "abnormally warm waters are predicted to continue to surface and expand westward over the course of the next three to four months." If these predictions hold, there's a strong potential for this El Niño event to peak as a very robust occurrence, possibly reaching or surpassing the NINO3.4 Index value of 2.0˚C between December 2023 and January 2024.