El Ni\~no Modoki thus far can be mostly predicted more than 10 years ahead of time

Abstract

The 2014-2015 "Monster"/"Super" El Ni\~no failed to be predicted one year earlier due to the growing importance of a new type of El Ni\~no, El Ni\~no Modoki, which reportedly has much lower forecast skill with the classical models. In this study, we show that, so far as of today, this new El Ni\~no actually can be mostly predicted at a lead time of more than 10 years. This is achieved through tracing the predictability source with an information flow-based causality analysis, which is rigorously established from first principles in the past decade. We show that the information flowing from the solar activity 45 years ago to the sea surface temperature results in a causal structure resembling the El Ni\~no Modoki mode. Based on this, a multidimensional system is constructed out of the sunspot number series with time delays of 22-50 years. The first 25 principal components are then taken as the predictors to fulfill the prediction, which through information flow-based causal deep learning reproduces rather accurately the events 12 years in advance.