Decadal Modulation of ENSO's Impact on North Tropical Atlantic SSTs by Tropical Pacific Precipitation

Abstract

El Niño–Southern Oscillation (ENSO) often induces sea surface temperature (SST) anomalies in the North Tropical Atlantic (NTA) during the following spring. However, the decadal stability of ENSO's impact and its underlying modulation mechanisms remain unclear. Based on the piControl runs from 40 Coupled Model Intercomparison Project Phase 6 climate models, this study reveals that ENSO's impact on NTA SSTs exhibits significant decadal variability. We find that this variability is modulated by the background intensity of wintertime precipitation over the central-eastern tropical Pacific. When the precipitation background state strengthens, the atmospheric Pacific–North American Teleconnection wave train responses to ENSO become more pronounced. These enhanced responses intensify westerly wind anomalies over the NTA, which in turn promotes local warming via the wind–evaporation–SST (WES) feedback. Additionally, increased precipitation in key regions enhances tropospheric heating, increasing atmospheric stability over the tropical Atlantic and further amplifying the NTA warming response. This study identifies tropical Pacific precipitation as a contributing mechanism behind the decadal variability of ENSO's impact on NTA SSTs, offering a new perspective on the factors that modulate ENSO's remote climate impacts.