[A-CG38] Science in the Arctic Region

[ACG38-P23] Understanding of hydrological circulation of Arctic region using ¹⁷O-excess variation in SIGMA-D ice core

*Akane Tsushima¹, Kumiko Goto Azuma², Sumito Matoba³, Naoko Nagatsuka², Teruo Aoki⁴, Koji Fujita⁵ (1.Research Institute for Humanity and Nature, 2.National Institute of Polar Research, 3.Institute of Low Temperature Science, Hokkaido Univ.,, 4.Okayama Univ., 5.Nagoya Univ.)

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.