Single- and multi-year ENSO events controlled by pantropical climate interactions
Ji‐Won Kim, Jin‐Yi Yu
Abstract
Abstract To better understand the diverse temporal evolutions of observed El Niño‒Southern Oscillation (ENSO) events, which are characterized as single- or multi-year, this study examines similar events in a 2200-year-long integration of Community Earth System Model, version 1. Results show that selective activation of inter- and intra-basin climate interactions (together, pantropical climate interactions) controls ENSO’s evolution pattern. When ENSO preferentially activates inter-basin interactions with tropical Indian and/or Atlantic Oceans, it introduces negative feedbacks into the ENSO phase, resulting in single-year evolution. When ENSO preferentially activates intra-basin interactions with subtropical North Pacific, it causes positive feedbacks, producing multi-year evolution. Three key factors (developing-season intensity, pre-onset Pacific condition, and maximum zonal location) and their thresholds, which determine whether inter- or intra-basin interactions are activated and whether an event will become a single- or multi-year event, are identified. These findings offer a way to predict ENSO’s evolution pattern by incorporating the controlling role of pantropical climate interactions.