01 Nov 2022
01 Nov 2022
Status: this preprint is currently under review for the journal TC.

Inferring horizontal asymmetry of the bulk ice crystal fabric from phase-sensitive radar measurements

Ole Zeising1, Tamara Annina Gerber2, Olaf Eisen1,3, M. Reza Ershadi4, Nicolas Stoll1,3, Ilka Weikusat1,4, and Angelika Humbert1,3 Ole Zeising et al.
  • 1Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
  • 2Section for the Physics of Ice, Climate and Earth, The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
  • 3Department of Geosciences, University of Bremen, Bremen, Germany
  • 4Department of Geosciences, Tübingen University, Tübingen, Germany

Abstract. The bulk crystal orientation in ice influences the flow of glaciers and ice streams. The ice c-axes fabric is most reliably derived from ice cores. Because these are sparse, the spatial and vertical distribution of the fabric in the Greenland and Antarctic ice sheets is largely unknown. In recent years, methods have been developed to determine fabric characteristics from radar measurements. The aim of this paper is to present an improved method to infer the horizontal fabric asymmetry by precisely determining the travel-time difference using co-polarised phase-sensitive radar data. We applied this method to six radar measurements from the EastGRIP drill site on Greenland's largest ice stream to give a proof-of-concept by comparing the results with the horizontal asymmetry of the bulk crystal anisotropy derived from the ice core. This comparison shows an almost perfect agreement, which is a large improvement compared to previously used methods. Our approach is particularly useful for determining the vertical profile of the fabric asymmetry in higher resolution and over larger depths than was achievable with previous methods, especially in regions with strong asymmetry.

Ole Zeising et al.

Status: open (until 27 Dec 2022)

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Ole Zeising et al.

Ole Zeising et al.


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Short summary
The flow of glaciers and ice streams is influenced by the crystal fabric orientation. Beside from sparse ice cores, these can be investigated by radar measurements. Here, we present an improved method which allows to infer the horizontal fabric asymmetry using polarimetric phase-sensitive radar data. A validation of the method on a deep ice core from the Greenland ice sheet shows near perfect agreement, which is a large improvement over previously used methods.