Elastic Constants of Artificial and Natural Ice Samples by Brillouin Spectroscopy

Abstract

AbstractThe method of Brillouin spectroscopy has been used to measure the dynamic elastic moduli of local homogeneous regions in ice samples representing four different environments of formation. These included artificial ice frozen from distilled water, clear monocrystalline glacial ice, bubbly lake ice, and sea ice. The samples studied were found to have identicallocalelastic properties. Accordingly the elastic properties of homogeneous monocrystalline ice have been found not to vary with sample age, with impurities present at the time of freezing, or with crystal quality. Thebulkelastic properties of ice remain, of course, subject to modification by different crystal grain textures and the presence of inclusions of various sorts. Because the elastic constants obtained in the present work are subject to smaller overall uncertainty than values measured previously, it is believed that they are the most reliable obtained to date. The values at −16 °C were determined to bec11= 139.29 ± 0.41,c12= 70.82 ± 0.39,c13= 57.65 ± 0.23,c33= 150.10 ± 0.46,c44= 30.14 ± 0.11 (units of 108N m− 2or kbar). A full range of derived elastic parameters for monocrystalline ice and for homogeneous isotropic polycrystalline ice has been calculated.