Paleoclimate reconstructions of El Niño/Southern Oscillation (ENSO) behavior often rely on oxygen isotopic records from tropical corals (
Coral oxygen isotopes (δ18O) from the central equatorial Pacific provide monthly resolved records of El Niño‐Southern Oscillation activity over past centuries to millennia. However, calibration studies using
- NSF-PAR ID:
- 10368304
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 48
- Issue:
- 24
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract δ 18O). However, few reef‐based observations of physical conditions during El Niño events exist, limiting our ability to interpret coralδ 18O. Here we present physical and geochemical measurements from Palmyra Atoll (5.9°N, 162.1°W) from 2014–2017, along with a data assimilation product using the isotope‐enabled Regional Ocean Modeling System (isoROMS). Coralδ 18O signals are comparably strong in 2014–2015 and 2015–2016; notably, over 50% of the signal is driven by seawaterδ 18O, not temperature. If a constant seawaterδ 18O:salinity relationship were present, this would imply a comparable salinity anomaly during both events. However, salinity changes are much larger during 2014–2015, indicating a highly nonstationary relationship. isoROMS then shows that advection strongly influencesδ 18O during both the 2014–2015 and 2015–2016 El Niño, driving differences in the salinity/seawaterδ 18O relationship. This demonstrates the need for considering ocean dynamics when interpreting coralδ 18O. -
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Abstract Explosive volcanic eruptions are one of the largest natural climate perturbations, but few observational constraints exist on either the climate responses to eruptions or the properties (size, hemispheric aerosol distribution, etc.) of the eruptions themselves. Paleoclimate records are thus important sources of information on past eruptions, often through the measurement of oxygen isotopic ratios (
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