Interannual and decadal variability of the western Pacific sea surface condition for the years 1787-2000: Reconstruction based on stable isotope record from a Guam coral

[ 1] We present a monthly resolved, 213-year stable isotope time series from a coral from Guam (13 degrees N, 145 degrees E), which is located on the northern edge of the western Pacific warm pool. Oxygen isotopic composition of the coral skeleton (delta O-18(coral)) shows seasonal, interannual, and decadal variability, which documents significant oceanographic changes related to thermal and hydrologic variations in this region. The delta O-18(coral) anomaly reflects sea surface temperature (SST) anomaly and sea surface salinity (SSS) anomaly with significant r values of - 0.69 and 0.49, respectively, which are strongly linked to oceanographic changes that occur during El Nino - Southern Oscillation (ENSO) warm and cool phases. We identified 46 ENSO warm ( El Nino) and 53 cool phases ( La Nina) in the coral record, which are consistent with those phases reconstructed by Nino 3.4 SST anomaly. Spectral analyses of the delta O-18(coral) anomaly record for the years 1790 - 1999 identified significant peaks around similar to 3 to similar to 7 years. These results indicate that the Guam coral has recorded ENSO periodicity. The delta O-18(coral) anomaly shows decadal variability of similar to 15- to similar to 45-year periodicity with significant shifts (< 0.2%) from warmer to cooler condition and vice versa. An accumulative decrease in delta O-18(coral) time series may imply similar to 0.75 degrees C warming of SST and similar to 0.23 parts per thousand freshening of seawater delta O-18, corresponding to a decrease of SSS by similar to 0.85, in the northwestern tropical Pacific over the last 2 centuries.