Western Pacific Warm Pool δ¹⁸O Response to the El Niño‐Southern Oscillation

Abstract Tropical Pacific seawater and precipitation stable oxygen isotope data aid in understanding modern oceanic and atmospheric interactions, and these data are particularly valuable as they are archived in isotope‐based paleoclimate records. However, the absence of modern seawater isotope time series limits the ability to identify the atmospheric influences on these data, precluding robust paleoclimate interpretations. We present a new 10 year sub‐monthly record of seawater and precipitation stable oxygen isotope values (δ 18 O sw and δ 18 O p ) from Koror, Palau. Our dataset indicates that temporally, δ 18 O sw is strongly influenced by local δ 18 O p. Both monthly δ 18 O sw and δ 18 O p are highly correlated with outgoing longwave radiation across the tropical Pacific, reflecting a Walker Circulation imprint on the surface ocean. Changes in the Palau δ 18 O sw —salinity relationship correspond to NINO3.4 variability, indicating a difference in how these variables record El Niño Southern Oscillation (ENSO) information, but demonstrating the utility of δ 18 O sw to reconstruct ENSO variability in the western tropical Pacific.