Abstract

Radar sounding is a geophysical technique that enables investigation of the subglacial and englacial properties of ice sheets. Typically, glaciological information is extracted from geometric analysis of radar images (e.g. bed topography and internal ice layering) or radiometric analysis of the power (e.g. subglacial water and ice temperature). However, recent advances in phase-sensitive radar sounding provide new opportunities to investigate `fine-scale’ englacial structure at length-scales beyond the conventional vertical resolution.

In the first part of the seminar I will describe a new phased-based polarimetric technique to measure ice fabric: the orientation distribution of ice crystals. Ice fabric is an important, but often overlooked, component of ice rheology and provides information about past ice deformation. I will describe application of the technique to slow-flowing ice in the NEEM divide region of Greenland, and fast-flowing ice in Rutford Ice Stream, West Antarctica (as part of the BEAMISH project). In the second part of the seminar I will describe proof-of-concept for estimation of englacial (vertical) velocity using repeat-pass interferometry applied to airborne radar sounding data. Previous estimation of englacial velocity has been done using the ground-based ApRES, and the adaptation to airborne data is a step toward mapping the 3D velocity structure of ice sheets.