Influence of Spring Precipitation over Maritime Continent and Western North Pacific on the Evolution and Prediction of El Niño-Southern Oscillation

Previous studies suggested that spring precipitation over the tropical western Pacific Ocean can influence the development of El Ni & ntilde;o-Southern Oscillation (ENSO). To identify crucial precipitation patterns for post-spring ENSO evolution, a singular value decomposition (SVD) method was applied to spring precipitation and sea surface temperature (SST) anomalies, and three precipitation and ENSO types were obtained with each highlighting precipitation over the Maritime Continent (MC) or western north Pacific (WNP). High MC spring precipitation corresponds to the slow decay of a multi-year La Ni & ntilde;a event. Low MC spring precipitation is associated with a rapid El Ni & ntilde;o-to-La Ni & ntilde;a transition. High WNP spring precipitation is related to positive north Pacific meridional mode and induces the El Ni & ntilde;o initiation. Among the three ENSO types, ocean current and heat content behave differently. Based on these spring precipitation and oceanic factors, a statistical model was established aimed at predicting winter ENSO state. Compared to a full dynamical model, this model exhibits higher prediction skills in the winter ENSO phase and amplitude for the period of 1980-2022. The explained total variance of the winter Ni & ntilde;o-3.4 index increases from 43% to 75%, while the root-mean-squared error decreases from 0.82 degrees C to 0.53 degrees C. The practical utility and limitations of this model are also discussed.