Editorial Type:
Article
Article Type:
Research Article

Surface Water Mixing in the Solomon Sea as Documented by a High-Resolution Coral 14C Record

T. P. Guilderson Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California

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D. P. Schrag Laboratory for Geochemical Oceanography and the Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts

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M. A. Cane Lamont-Doherty Earth Observatory and the Department of Earth and Environmental Sciences, Columbia University, Palisades, New York

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Print Publication:
01 Mar 2004
DOI:
https://doi.org/10.1175/1520-0442(2004)017<1147:SWMITS>2.0.CO;2
Page(s):
1147–1156
Restricted access

Abstract

A bimonthly coral-based record of the postbomb radiocarbon content of Solomon Sea surface waters is interpreted to reflect mixing of subtropical surface water and that advected in from the east by the equatorial branch of the South Equatorial Current (SEC). Annual mean Δ14C has a dynamic range of nearly 175‰, with a total range of nearly 200‰. Prebomb values average −56‰ and the annual mean postbomb maxima occurs in 1985 with a value of +117%. Interannual variability in the record reflects surface current variations in conjunction with surface wind changes associated with ENSO. During El Niño years the waters of the Solomon Sea reflect a stronger influence of waters advected in from the east by the SEC and less “pure” subtropical water. This is most likely accomplished by a southward shift of the equatorward branch of the SEC during El Niño. There is an overall decrease in the relative proportion of eastern tropical water that is interpreted as a decrease in the strength and intensity of the shallow circulation of the tropical Pacific during the latter portion of the twentieth century. If validated, this secular trend bears strongly upon the rate of extratropical–tropical recirculation and the redistribution of heat and salt within the tropical Pacific.

Additional affiliation: Department of Ocean Sciences and Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, California

Corresponding author address: Dr. Thomas P. Guilderson, Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94551. Email: guilderson1@llnl.gov

Abstract

A bimonthly coral-based record of the postbomb radiocarbon content of Solomon Sea surface waters is interpreted to reflect mixing of subtropical surface water and that advected in from the east by the equatorial branch of the South Equatorial Current (SEC). Annual mean Δ14C has a dynamic range of nearly 175‰, with a total range of nearly 200‰. Prebomb values average −56‰ and the annual mean postbomb maxima occurs in 1985 with a value of +117%. Interannual variability in the record reflects surface current variations in conjunction with surface wind changes associated with ENSO. During El Niño years the waters of the Solomon Sea reflect a stronger influence of waters advected in from the east by the SEC and less “pure” subtropical water. This is most likely accomplished by a southward shift of the equatorward branch of the SEC during El Niño. There is an overall decrease in the relative proportion of eastern tropical water that is interpreted as a decrease in the strength and intensity of the shallow circulation of the tropical Pacific during the latter portion of the twentieth century. If validated, this secular trend bears strongly upon the rate of extratropical–tropical recirculation and the redistribution of heat and salt within the tropical Pacific.

Additional affiliation: Department of Ocean Sciences and Institute of Marine Sciences, University of California, Santa Cruz, Santa Cruz, California

Corresponding author address: Dr. Thomas P. Guilderson, Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94551. Email: guilderson1@llnl.gov

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