HR: 1330h
AN: PP52A-0955    [PDF]
TI: Assessing the Reproducibility of Coral-based Climate Records: A Multi-proxy Replication Test using Three Porites lutea Coral Heads from a Reef Offshore Amedee Island, New Caledonia
AU: * Stephans, C L
EM: stephans@seas.marine.usf.edu
AF: College of Marine Science, University of South Florida, 140 7th Ave., South, St. Petersburg, FL 33701 United States
AU: Quinn, T M
EM: quinn@seas.marine.usf.edu
AF: College of Marine Science, University of South Florida, 140 7th Ave., South, St. Petersburg, FL 33701 United States
AU: Taylor, F W
EM: fred@utig.ig.utexas.edu
AF: Institute for Geophysics, Univ. Texas at Austin, 4412 Spicewood Springs Rd., Austin, TX 78759-8500 United States
AU: Correge, T
EM: correge@noumea.ird.nc
AF: UR055 Paleotropique, Institut de Recherche pour le Developpement, IRD, Noum‚a, BPA5 New Caledonia
AB: Coral-based climate studies commonly use elemental ratios and stable isotopes of coral skeletons to address seawater temperature and hydrologic balance issues in the tropical surface oceans. Cross-checking, a standard technique used in paleoclimatology to access the fidelity of proxy records, has not been widely applied in coral-based climate studies, primarily because of the time and cost associated with generating multiple records from a single reef site. Modern and paleoclimate reconstructions based on a single proxy-coral record from a site may contain errors if individual corals from the same reef record different geochemical signals. In this study we perform a replication test using elemental ratios and stable isotopes in multiple corals from New Caledonia. The reef complex offshore Amedee Island, New Caledonia is an ideal site to perform a coral replication test because instrumental sea surface temperatures (SST) and sea surface salinity measurements (SSS) have been made there for over 25 years. In this study, we compare sub-monthly resolved, geochemical variations (Sr/Ca, $\delta^{18}$O and $\delta^{13}$C) in three Porites lutea coral heads, located $\sim$500 m apart, with the instrumental SST and SSS records over the interval 1992-1964. The monthly coral Sr/Ca and $\delta^{18}$O time series are well correlated to each other (r=0.86) and to the monthly instrumental SST record (r=-0.86, coral Sr/Ca to SST; r=-0.77, coral $\delta^{18}$O to SST). The three, sub-monthly resolved, $\sim$30 year coral Sr/Ca-SST time series have mean SST values that agree within $0.2\deg$C from the instrumental mean SST value. A similar comparison for the coral $\delta^{18}$O-SST records indicate a maximum difference between predicted and observed mean SST of $0.5\deg$C. Analysis of the monthly climatological means also indicates that Sr/Ca-SST records closely match the instrumental SST record ($\pm0.4\deg$C); a similar comparison using the $\delta^{18}$O-SST record yields an average offset of $\pm0.6\deg$C between observed and predicted monthly SST. Stacking the three records to form a composite Sr/Ca-SST and $\delta^{18}$O-SST records does not appreciably improve the goodness of fit between the proxy and instrumental SST records; hence a coral-based proxy climate record from a single coral accurately reflects the observed record of climate variability at this locality.
DE: 1620 Climate dynamics (3309)
DE: 3309 Climatology (1620)
DE: 3344 Paleoclimatology
DE: 4215 Climate and interannual variability (3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting