Keywords:Ice core, 17O-excess, Greenland
The stable water isotope ratios (δ18O, δD and d-excess which is clculated from δD and δ18O) in ice cores are important proxy of paleo climate change. Recently, δ17O and 17O−excess which is clculated from δ18O and δ17O have attracted attention as a promising new proxy of hydro-climate variation. In this study, we measured δ17O, δ18O and δD in an ice core, which was obtained from the northwest Greenland using Wavelength-Scanned Cavity Ring-Down Spectroscopy (model L2140-i; Picarro) with high precision at the National Institute of Polar Research. And we also calculated d-excess and 17O-excess form those. For last 80 years, the correlation of 17O-excess and d-excess is definitely changed with period of 10 to 20 years. The correlation of those shifted in 1967, that is, we showed sea-level pressure in periods 1(1949-1967) and 2(1968-1980) (NCEP Reanalysis data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/printpage.pl). During the periods 2, the high-pressure area extended across the whole Greenland, therefore, water vapor was hard to reach to SIDMA-D site. We think that the moisture influx route to SIGMA-D site and its amount changed due to the climate field change, resulting the changes of those correlations.