Relationship between Pacific–South America teleconnections in austral fall and ENSO evolution

South Pacific atmospheric teleconnections and their relationship with the tropical Pacific have remained less explored than their North Pacific counterparts. Using observational reanalysis datasets since the mid-20th century, we first identified three atmospheric teleconnections by applying Empirical Orthogonal Function (EOF) analysis to the 200hPa geopotential height from the South Pacific to South America during the austral fall, when the variability of El Niño–Southern Oscillation (ENSO) is weak. We then investigated the relationship between these EOFs and ENSO. We found that EOF1 is a direct Rossby wave response to the tropical convection associated with previous ENSO events. In contrast, both EOF2 and EOF3—similar to Pacific–South America teleconnections—are significantly correlated with subsequent ENSO events. In detail, EOF2 exhibits a great-circle Rossby wave energy propagation pattern, initiated by enhanced convection over the equatorial western Pacific. That is, this convection is largely responsible for the development of both ENSO and EOF2. Meanwhile, EOF3 is characterized by wave energy propagation toward the tropical Pacific from the high-latitudes, potentially contributing to ENSO development. These results suggest that further investigation of tropical–South Pacific interactions could expand our understanding of Pacific climate variability.