Competition between grain growth and grain size reduction in polar ice

• Main Authors: Rößiger, J., Bons, P. D., Griera, A., Jessell, M. W., Evans, L., Montagnat, M., Kipfstuhl, Sepp, Faria, S. H., Weikusat, Ilka
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: INT GLACIOL SOC 2011
• Subjects: ice core; Journal of Glaciology
• Online Access: https://epic.awi.de/id/eprint/23801/; https://epic.awi.de/id/eprint/23801/1/Roessiger2011.pdf; https://hdl.handle.net/10013/epic.39010; https://hdl.handle.net/10013/epic.39010.d001

Static (or ‘normal’) grain growth, i.e. grain boundary migration driven solely by grain boundary energy, is considered to be an important process in polar ice. Many ice-core studies report a continual increase in average grain size with depth in the upper hundreds of metres of ice sheets, while at deeper levels grain size appears to reach a steady state as a consequence of a balance between grain growth and grain-size reduction by dynamic recrystallization. The growth factor k in the normal grain growth law is important for any process where grain growth plays a role, and it is normally assumed to be a temperature-dependent material property. Here we show, using numerical simulations with the program Elle, that the factor k also incorporates the effect of the microstructure on grain growth. For example, a change in grain-size distribution from normal to log-normal in a thin section is found to correspond to an increase in k by a factor of 3.5.