DOI: 10.25921/sncz-6m98
title: NOAA/WDS Paleoclimatology - Malindi - Coral d18O Data

description: A 194-year annual record of skeletal d18O from a coral growing at Malindi, Kenya, preserves a history of sea surface temperature (SST) change that is coherent with instrumental and proxy records of tropical Pacific climate variability over interannual to decadal periods. This variability is superimposed on a warming of as much as 1.3C since the early 1800s. These results suggest that the tropical Pacific imparts substantial decadal climate variability to the western Indian Ocean and, by implication, may force decadal variability in other regions with strong El Nino-Southern Oscillation teleconnections.
description: File includes columns for Year AD, Coral d18O (‰), and SST (°C). The SST data are sparse as they were screened using the procedures described below. The coral used in this study grew (and still does grow) in Malindi Marine Park, Kenya (3°S, 40°E). The colony lies at a depth of ~6m (low tide) and is about 4m in height. Annual growth rates are roughly 12mm/yr. Oxygen isotopic data are from annual increments of coral skeleton that were cut according to annual density bands that are clearly visible in the core. Annual chunks were crushed and homogenized; isotopic values represent the average of duplicate or triplicate samples. Because samples were taken with respect to visible annual density banding, there is no depth scale for this record. Annual density banding is unambiguous in this core, so annual assignments are precise. The annual samples represent a year that is roughly November thru October. (The year assigned is the year of the January, not the year of the November, that is included in that interval). However, if cuts were not precisely along the October-November boundary, small (1-2 month) offsets in the months assigned to an annual sample may have occurred. Stable isotope samples were analyzed on three isotope ratio mass spectrometers: a VG 602 with SIRA-series electronics at Rice University, a VG-SIRA with automated carbonate preparation device, and a Micromass Optima with automated carbonate preparation device, the latter two at the University of Colorado/Boulder (INSTAAR). Each measurement has an analytical uncertainty of ±0.08‰; the differences between duplicate samples were above 0.18‰ in only 2 of 195 cases, confirming inter-lab and inter-instrument calibrations. We calibrate the coral d18O to the enhanced COADS SST from 3°S, 41°E, which has a broader screening tolerance than the standard COADS (4.5 sigma vs. 3.5 sigma) to capture larger anomalies. COADS enhanced data are provided by the NOAA-CIRES Climate Diagnostics Center, Boulder, Colorado, from their web site at http://www.cdc.noaa.gov/. We use annual SST data representing a Nov.-Oct. year and include only years that contain at least three observations from every month; this procedure yields a slope of 0.256‰ per 1°C and explains 47% of the SST variance. The details of the calibration procedure have little effect on the paleotemperature slope: using the standard SST product instead of the enhanced yields a slope of -0.228; omitting the minimum requirement of three observations per month yields a slope of 0.262 for the enhanced COADS and 0.252 for the standard. These correlations are all significant at >99.9%. More information on this record can be found in the original reference.