Research on strong El Niños has shown that they may be a result of a stronger-than-normal North Equatorial Counter Current, itself triggered by lower-than-normal sea levels that develop early in the year. A numerical model study of the 1981–1982 El Niño shows that the low sea levels are due to local winds in the west Pacific, and this is shown also to be true for the 1997–1998 and 2015–2016 El Niños. As a result, we now have a much better understanding of the mechanism causing strong El Niños.

In conflict with conventional theory, recent analysis of data from a high-resolution global ocean model showed that the North Equatorial Counter Current was responsible for the unusually warm water which triggered the strong El Niños of 1982–83 and 1997–98. In this paper some of the key physics deduced from the model results are tested against satellite data from the 1997–98 event. The results show that the model closely followed reality during the period, further supporting the new mechanisms.