Non‐Stationary Relationship Between Northeast Pacific Sea Surface Temperature and El Niño‐Southern Oscillation

Abstract El Niño‐Southern Oscillation (ENSO) is the most pronounced interannual variability over the tropical Pacific, exerting profound influences on global climate. In the mid‐latitude Northeast Pacific (NEP), persistent sea surface temperature anomalies (SSTAs) have attracted wide attention in recent decades and have been linked to tropical variability. Considering their important climate impacts and potential linkages, this study investigates the non‐stationary relationship between SSTAs in the NEP (SSTA NEP ) and ENSO using correlation decomposition and Linear Inverse Modeling. Our analysis reveals notable shifts in the SSTA NEP ‐ENSO linkage during 1961–2022. Before 1980, SSTA NEP exhibited minimal influence on ENSO evolution. Conversely, during 1981–2000, SSTA NEP substantially contributed to ENSO development, primarily via the North Pacific Meridional Mode. However, after 2000, this relationship has weakened again, suggesting a complex interplay between SSTA NEP and ENSO. Understanding these relationship shifts is essential for advancing ENSO predictability and thereby enhancing the reliability of seasonal‐to‐decadal climate prediction.