What radar reveals about crystal orientation: A study from Greenland Ice Sheet

• Main Authors: Zeising, Ole, Eisen, Olaf, Weikusat, Ilka, Humbert, Angelika
• Format: Conference Object
• Language: unknown
• Published: 2019
• Subjects: Antarctic; Greenland; The Antarctic; Antarc*; East Greenland; ice core; Ice Sheet
• Online Access: https://epic.awi.de/id/eprint/49817/; https://epic.awi.de/id/eprint/49817/1/IGS_PpRES_Greenland_ozeising.pdf; https://hdl.handle.net/10013/epic.3a8b9f48-dae7-4905-a683-6a5aca8fca8b; https://hdl.handle.net/

Deformation processes dominated by dislocation activity within ice sheets take place on small scale: ice crystals are effectively re-oriented to minimize resistance when deformation takes place. The analysis of Crystal Orientation Fabric (COF) of c-axes in ice cores is a well-established technique to investigate these processes within ice sheets. Due to the extensive infrastructure required for drilling and protracted analysis of ice cores, the amount of information of COF of the Antarctic and Greenland Ice Sheet is limited, both, in aerial coverage as well as in depth resolution. Indirect measurements, such as geophysical techniques, provide complementary information. Depending on whether the COF is isotropic or anisotropic, a radar signal is propagating differently in terms of angle of incidence and polarization, and, partially reflected when COF properties change along the direction of travel. We study the ability of phase-sensitive radar measurements to infer an overall pattern of COF by comparing our results to COF derived from the EastGRIP ice core, drilled into the North East Greenland Ice Stream (NEGIS). If radar measurements allow to reveal information about the COF as analyzed ice cores do, this would provide important additional information on the (an)isotropy at locations where no ice core is available. Furthermore, it has the ability to offer a quasi-continuous spatial coverage and to greatly improve our understanding of the evolution of anisotropy along ice-flow trajectories, from ice divides to the calving front of outlet glaciers.