[A-CC37] [EJ] Ice cores and past environmental changes

[ACC37-P09] Variation trend of ¹⁷O-excess in an Arctic ice core

★Invited papers

*Akane Tsushima¹, Vasileios Gkinis², Kumiko Goto-Azuma³, Sumito Matoba⁴, Hideaki Motoyama³ (1.Research Institute for Humanity and Nature, 2.Niels Bohr Institute, University of Copenhagen, 3.National Institute of Polar Research, 4.Institute of Low Temperature Science, Hokkaido University)

Keywords:ice core, Arctic region, 17O-excess

Ice cores obtained from glaciers and ice sheets are important archives for reconstructing changes in the paleoclimate. The most important climate changes, such as the variation in temperature, precipitation, and the hydrological cycle, are reconstructed from stable water isotope ratios (δ¹⁸O, δD, and a second-order parameter, the d-excess, defined as d−excess = δD − 8δ¹⁸O) measured in ice cores.
With the improvment of water isotope analyzers, the ability to measure δ¹⁷O in water with high precision provided another second−order parameter, the ¹⁷O−excess, defined as ¹⁷O−excess = ln (δ¹⁷O+1) − 0.528 ∗ ln(δ¹⁸O+1). Previous studies reported that ¹⁷O−excess in polar snow is mainly controlled by the relative humidity in the water vapor source region, therefore expected as a new proxy of past climate change. However, at the present, there are few studies of ¹⁷O−excess in ice core, and therefore an undrestanding of variation factor of that is incomplete.
In this study, we analyzed δ¹⁷O and ¹⁷O−excess in an ice core which was drilled in Alaska. We also discussed the variation factors of those associated with environmental change.