GROWTH PROCESS OF AIR-HYDRATES AND DIFFUSION OF AIR MOLECULES IN DEEP ICE SHEET

• Main Authors: ウチダ ツトム, マエ シンジ, ホンドウ タケオ, カワバタ ジュンイチ, Tsutomu UCHIDA, Shinji MAE, Takeo HONDOH, Vladimir Ya. LIPENKOV, Paul DUVAL, Junichi KAWABATA
• Format: Report
• Language: English
• Published: Hokkaido National Industrial Research Institute 1994
• Subjects: Ice Sheet; Polar meteorology and glaciology; Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3831; http://id.nii.ac.jp/1291/00003831/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3831&item_no=1&attribute_id=18&file_no=1

Geometrical parameters of air-hydrate crystals in Vostok ice cores revealed that air-hydrate crystals were growing in the deep ice sheet. Air-hydrate crystals with radius of 65 to 100μm grew while smaller crystals dis-appeared. Moreover, the smaller the crystal was, the quicker its number concen-tration decreased. A growth model of air-hydrate crystals in ice sheets was developed by assuming the spherical diffusion field of gas molecules and their steady state diffusions. The model with the given geometrical parameters gave an estimate that the product of the diffusion coefficient and equilibrium concen-tration of gas molecules in ice is of order 10^<-19> m^2 s^<-1> under the conditions of the deep ice sheet. This estimate is reasonable if the concentration of gas molecules in ice is assumed to be the same as that of self-interstitial of ice. The results indicate that gas molecules could diffuse several tens of centimeters during 100 kyr.