raw data

A 2.5-m-long core (SWGM03–01) was collected from a Porites sp. colony at 6 m below mean sea level on 16 March 2002. The core was drilled vertically from the top of the colony and then cut into 7-mm-thick slabs in the laboratory. The δ18Ocoral values of samples covering the period from 1890 to 2002 was analyzed using an online system comprising an IsoPrime Isotope-ratio mass spectrometer (GV Instruments Ltd.) coupled to a Multicarb automatic sample treatment system at the Geological Survey of Japan (GSJ), whereas the δ18Ocoral values of samples predating 1890 were determined by the Center for Advanced Marine Core Research at Kochi University (KCC) using a same system used at GSJ. All δ18Ocoral data were normalized to Vienna Pee Dee Belemnite (V-PDB) using the NBS-19 standard (δ18O = +2.2‰) from the U.S. National Institute of Standards and Technology. The International Atomic Energy Agency standard IAEA-603 (δ18O = –2.37 ± 0.04‰) was also used for some measurements conducted at KCC. The standard deviations of replicate δ18O measurements of the standards during the mass spectrometer runs were 0.04‰ (1s) and < 0.10‰ (1s) at GSJ and KCC, respectively.