El Niño Pacing Orchestrates Inter‐Basin Pacific‐Indian Ocean Interannual Connections

Abstract El Niño‐Southern Oscillation (ENSO), the primary source of year‐to‐year climate variability on Earth, has profound impacts on the Indian Ocean dipole (IOD), another important climate pattern. Much attention has been paid to potentially increased ENSO predictability by utilizing IOD conditions, inferred from a statistically significant correlation with ENSO at a long lead time. However, the intrinsic dynamics for the causality of this IOD‐ENSO relationship remain largely elusive. Here, we demonstrate that the observed nonstationary IOD‐ENSO lead‐lag relationship is mainly ENSO‐driven and therefore adds no additional information for ENSO predictability. The nonstationarity of their correlation is a manifestation of ENSO cycle complexity. Multi‐climate model and theoretical results further demonstrate that ENSO pacing tightly controls the statistical IOD‐ENSO relationship via changes in ENSO periodicity and regularity. This highlights that ENSO dominates the inter‐basin Pacific‐Indian Ocean interactions, shedding light on the key predictors for interannual pantropical climate variability.