TY - JOUR
T1 - Spatiotemporal variability in the δ18O-salinity relationship of seawater across the tropical Pacific Ocean
AU - Conroy, Jessica L.
AU - Thompson, Diane M.
AU - Cobb, Kim M.
AU - Noone, David
AU - Rea, Solanda
AU - Legrande, Allegra N.
N1 - Funding Information:
We are grateful for the dedicated water samplers who enabled this research: Lori J. Bell and Gerda Ucharm of the Coral Reef Research Foundation, Palau; Rosa Maritza Motoche González and the Fuerza Aérea Ecuatoriana, Santa Cruz, Galápagos, Ecuador; Taonateiti Kabiri and the students of Tennessee Primary School, London, Kiritimati; and the Manus Weather Observers, U.S. Department of Energy ARM Climate Research Facility, Manus, Papua New Guinea. We would like to thank the Galápagos National Park, the Kiritimati Ministry of Environment Lands and Agricultural Development for sample permits, and the Charles Darwin Research Station for logistical support. Funding sources for this work includes NSF-AGS-PF 1049664 to J.L.C., NSF P2C2-1203785 to K.M.C., J.L.C., and D.N. This research was also supported by the Office of Biological and Environment Research of the U.S. Department of Energy as part of the Atmospheric Radiation Measurement Climate Research Facility. Isotope data are available as supporting information associated with the manuscript.
Publisher Copyright:
©2017. American Geophysical Union. All Rights Reserved.
PY - 2017/5/1
Y1 - 2017/5/1
N2 - The relationship between salinity and the stable oxygen isotope ratio of seawater (δ18Osw) is of utmost importance to the quantitative reconstruction of past changes in salinity from δ18O values of marine carbonates. This relationship is often considered to be uniform across water masses, but the constancy of the δ18Osw-salinity relationship across space and time remains uncertain, as δ18Osw responds to varying atmospheric vapor sources and pathways, while salinity does not. Here we present new δ18Osw-salinity data from sites spanning the tropical Pacific Ocean. New data from Palau, Papua New Guinea, Kiritimati, and Galápagos show slopes ranging from 0.09 ‰/psu in the Galápagos to 0.32‰/psu in Palau. The slope of the δ18Osw-salinity relationship is higher in the western tropical Pacific versus the eastern tropical Pacific in observations and in two isotope-enabled climate model simulations. A comparison of δ18Osw-salinity relationships derived from short-term spatial surveys and multiyear time series at Papua New Guinea and Galápagos suggests spatial relationships can be substituted for temporal relationships at these sites, at least within the time period of the investigation. However, the δ18Osw-salinity relationship varied temporally at Palau, likely in response to water mass changes associated with interannual El Niño–Southern Oscillation (ENSO) variability, suggesting nonstationarity in this local δ18Osw-salinity relationship. Applying local δ18Osw-salinity relationships in a coral δ18O forward model shows that using a constant, basinwide δ18Osw-salinity slope can both overestimate and underestimate the contribution of δ18Osw to carbonate δ18O variance at individual sites in the western tropical Pacific.
AB - The relationship between salinity and the stable oxygen isotope ratio of seawater (δ18Osw) is of utmost importance to the quantitative reconstruction of past changes in salinity from δ18O values of marine carbonates. This relationship is often considered to be uniform across water masses, but the constancy of the δ18Osw-salinity relationship across space and time remains uncertain, as δ18Osw responds to varying atmospheric vapor sources and pathways, while salinity does not. Here we present new δ18Osw-salinity data from sites spanning the tropical Pacific Ocean. New data from Palau, Papua New Guinea, Kiritimati, and Galápagos show slopes ranging from 0.09 ‰/psu in the Galápagos to 0.32‰/psu in Palau. The slope of the δ18Osw-salinity relationship is higher in the western tropical Pacific versus the eastern tropical Pacific in observations and in two isotope-enabled climate model simulations. A comparison of δ18Osw-salinity relationships derived from short-term spatial surveys and multiyear time series at Papua New Guinea and Galápagos suggests spatial relationships can be substituted for temporal relationships at these sites, at least within the time period of the investigation. However, the δ18Osw-salinity relationship varied temporally at Palau, likely in response to water mass changes associated with interannual El Niño–Southern Oscillation (ENSO) variability, suggesting nonstationarity in this local δ18Osw-salinity relationship. Applying local δ18Osw-salinity relationships in a coral δ18O forward model shows that using a constant, basinwide δ18Osw-salinity slope can both overestimate and underestimate the contribution of δ18Osw to carbonate δ18O variance at individual sites in the western tropical Pacific.
KW - paleoclimate
KW - salinity
KW - seawater
KW - stable oxygen isotope
KW - tropical Pacific
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U2 - 10.1002/2016PA003073
DO - 10.1002/2016PA003073
M3 - Article
AN - SCOPUS:85018894140
VL - 32
SP - 484
EP - 497
JO - Paleoceanography and Paleoclimatology
JF - Paleoceanography and Paleoclimatology
SN - 2572-4517
IS - 5
ER -