Validation of Predicted Weak El Niño/La Niña Event during Water Year 2013

Based on a recent finding of the predictability of El Niño/La Niña events (see accompanying paper), water year 2013 (October 1, 2012, to September 30, 2013) was expected to be a weak El Niño/La Niña year. In light of this finding, this paper revisits the definitions of El Niño/La Niña events, provides a new perspective to these events as a single natural phenomenon that is characterized by predictable oscillations of the Earth and Moon's orbital forcings, and presents the validation results of predicted weak El Niño/La Niña event during the current water year of 2013. The association of analogous oscillatory orbital forcings of the Earth and Moon and Niño 3.4 index is shown using available real-time data during the current water year. Potential applications of the validity of this association are also discussed.