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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 (δ18Oswand δ18Op) from Koror, Palau. Our dataset indicates that temporally, δ18Oswis strongly influenced by local δ18Op.Both monthly δ18Oswand δ18Opare highly correlated with outgoing longwave radiation across the tropical Pacific, reflecting a Walker Circulation imprint on the surface ocean. Changes in the Palau δ18Osw—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 δ18Oswto reconstruct ENSO variability in the western tropical Pacific.
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Equatorial Undercurrent Influence on Surface Seawater δ 18 O Values in the Galápagos
Abstract Stable isotopes of oxygen (δ18O) in seawater reflect the combined influences of ocean circulation and atmospheric moisture balance. However, it is difficult to disentangle disparate ocean and atmosphere influences on modern seawater δ18O values, partly because continuous time series of seawater δ18O are rare. Here we present a nearly nine‐year, continuous record of seawater δ18O values from the Galápagos. Seawater δ18O values faithfully track sea surface salinity and salinity along the equator at 50 m depth. Zonal current velocity within the Equatorial Undercurrent (EUC), directly west of the Galápagos, is strongly correlated with Galápagos surface seawater δ18O values with a 1‐month lag. Reconstructions of Galápagos seawater δ18O values could thus provide a window into past variations in the strength of the EUC, an important influence on large‐scale tropical Pacific climate.
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- Award ID(s):
- 1847791
- PAR ID:
- 10396946
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 50
- Issue:
- 4
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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