El Nino Diversity Across Boreal Spring Predictability Barrier

El Nino exerts widespread hydroclimate impacts during boreal summer. However, the current prediction of El Nino across boreal spring has the most severe forecast errors, partially due to the lack of understanding diversified El Nino onset and decay. Here we show, through nonlineark-means cluster analysis of evolutions of 40 El Nino events since 1870, El Nino exhibits complex and diverse flavors in its onset and decay across boreal spring predictability barrier. We detected three types of El Nino onset and three types of decay. Each type exhibits distinct coupled dynamics, precursors, and hydroclimate impacts. The results guide the prediction of different types of El Nino transition amid spring predictability barrier and global land precipitation during early and late boreal summer. The new classification offers a metric to evaluate performances of climate models and to project future change of El Nino properties and its predictability.