The impact of temperature and crystal orientation fabric on the dynamics of mountain glaciers and ice streams

• Published in: Journal of Glaciology
• Main Authors: Hruby, Kate, Gerbi, Christopher, Koons, Peter, Campbell, Seth, Martín, Carlos, Hawley, Robert
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2020
• Subjects: Journal of Glaciology
• Online Access: http://nora.nerc.ac.uk/id/eprint/528331/; https://nora.nerc.ac.uk/id/eprint/528331/1/impact_of_temperature_and_crystal_orientation_fabric_on_the_dynamics_of_mountain_glaciers_and_ice_streams.pdf; https://www.cambridge.org/core/journals/journal-of-glaciology/article/impact-of-temperature-and-crystal-orientation-fabric-on-the-dynamics-of-mountain-glaciers-and-ice-streams/538918B695F492BE8FB8A836A3AF2AC8

Streaming ice accounts for a major fraction of global ice flux, yet we cannot yet fully explain the dominant controls on its kinematics. In this contribution, we use an anisotropic full-Stokes thermomechanical flow solver to characterize how mechanical anisotropy and temperature distribution affect ice flux. For the ice stream and glacier geometries we explored, we found that the ice flux increases 1–3% per °C temperature increase in the margin. Glaciers and ice streams with crystallographic fabric oriented approximately normal to the shear plane increase by comparable amounts: an otherwise isotropic ice stream containing a concentrated transverse single maximum fabric in the margin flows 15% faster than the reference case. Fabric and temperature variations independently impact ice flux, with slightly nonlinear interactions. We find that realistic variations in temperature and crystallographic fabric both affect ice flux to similar degrees, with the exact effect a function of the local fabric and temperature distributions. Given this sensitivity, direct field-based measurements and models incorporating additional factors, such as water content and temporal evolution, are essential for explaining and predicting streaming ice dynamics.