Common Signals in Tree-Ring Oxygen Isotope Ratios between Korea and Japan as Indicated by Summer Hydroclimate

Abstract

Tree-ring oxygen isotope ratios serve as high-resolution annual proxies for paleoclimate reconstruction. In East Asia, this proxy has been extensively utilized to reconstruct hydrological variability associated with monsoon dynamics. South Korea initiated tree-ring oxygen isotope ratios research for paleoclimate reconstruction from 2017. This study aims to evaluate common spatiotemporal patterns and climate factors between Japanese and Korean oxygen isotope chronologies.A total of seven sampling sites were strategically selected across South Korea based on topographic characteristics determined by major mountain ranges. At each site, above 10 increment cores were collected from Pinus densiflora, a widely distributed coniferous species throughout Korea. Oxygen isotope chronologies were developed using four trees with the greatest number of tree rings from each site. The ratio of oxygen isotope was measured annually using a TC/EA-IRMS (Research Institute for Humanity and Nature, Kyoto, 2019; currently at Nagoya University) following the alpha cellulose extraction through chemical processing.