Figure 3: Monthly Sr/Ca and δ18O records of Tahiti Porites corals.
From: Pronounced interannual variability in tropical South Pacific temperatures during Heinrich Stadial 1
Monthly coral Sr/Ca records (left panel), 2–7 year Gaussian band-pass filtering of monthly anomaly records (middle panel) and multitaper method spectral analysis (significance relative to a red noise null hypothesis determined with the robust method of noise background estimation60; number of tapers, 3; bandwidth parameter, 2; 95 and 99% confidence levels indicated; significant spectral peaks labelled) of detrended and normalized monthly anomaly records (right panel) for (a) a Heinrich Stadial 1 coral (15.0 kyr BP) and (b) a modern coral20 (average record of cores TH1 and TH2 drilled from two individual colonies). Local Tahiti SST is available from 1979–1991 (ref. 31). There is a limitation of coral Sr/Ca in recording the very high SST of 1984. Coral-based SST anomalies (respective mean was subtracted), using our seasonal Tahiti coral Sr/Ca-SST relationship of 0.057 mmol mol−1 per 1 °C are shown. (c) Monthly NINO3.4 index35 (SST anomalies in the central equatorial Pacific: 170°–120°W, 5°N–5°S) and corresponding band-pass filtering and spectral analysis. (d,e) As in (a,b), but for monthly coral δ18O records. The age of the fossil coral is given in thousand years before present (kyr BP), where 'present' refers to AD 1950.
