Isotopic fractionation of water during snow formation: Experimental evidence of kinetic effect

• Main Authors: Uemura,Ryu, Matsui,Yohei, Yoshida,Naohiro, Abe,Osamu, Mochizuki,Shigeto
• Format: Report
• Language: English
• Published: Department of Environmental Science and Technology, Tokyo Institute of Technology/SORST Project, Japan Science and Technology Corporation/Department of Environmental Science and Technology, Tokyo Institute of Technology/Snow and Ice Research Group, National Research Institute for Earth Science and Disaster Prevention/Snow and Ice Research Group, National Research Institute for Earth Science and Disaster Prevention 2005
• Subjects: water isotope; kinetic fractionation; artificial snow; deuterium excess; Polar meteorology and glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=2984; http://id.nii.ac.jp/1291/00002984/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=2984&item_no=1&attribute_id=18&file_no=1

Deuterium excess(d-excess=δD-8・δ^(18)O), which is calculated using two water isotope ratios(δD and δ^(18)O), is an indicator of kinetic isotope fractionation. The d-excess value reflects the evaporation process from the ocean or ice-crystal growth. Consequently, d-excess records preserved in ice cores may provide a climatic history of ocean surface conditions at the vapor source area. J. Jouzel and L. Merlivat(J. Geophys. Res., 89, 11749, 1984) proposed an isotope model to analyze information from ice cores. That model includes kinetic fractionation during snow formation, depending on the degree of the supersaturation ratio of vapor. However, no experiment was conducted under the controlled supersaturation ratio. Experiments described herein measured the isotopic ratios of the vapor and artificial snow produced under a controlled supersaturation ratio to confirm the kinetic isotope effect experimentally. Results indicate a higher d-excess value for ice crystals at a higher vapor supersaturation ratio and provide experimental evidence for the kinetic effect during snow formation.