Publication Date:
2017-10-20
Description:
Radar data (center frequency 150 MHz) collected on the Antarctic plateau near the EPICA
deep-drilling site in Dronning Maud Land vary systematically in backscattered power, depending on the
azimuth antenna orientation. Backscatter extrema are aligned with the principal directions of surface
strain rates and change with depth. In the upper 900 m, backscatter is strongest when the antenna
polarization is aligned in the direction of maximal compression, while below 900m the maxima shift
by 90◦ pointing towards the lateral flow dilatation. We investigate the backscatter from elongated air
bubbles and a vertically varying crystal-orientation fabric (COF) using different scattering models in
combination with ice-core data. We hypothesize that short-scale variations in COF are the primary
mechanism for the observed anisotropy, and the 900m boundary between the two regimes is caused by
ice with varying impurity content. Observations of this kind allow the deduction of COF variations with
depth and are potentially also suited to map the transition between Holocene and glacial ice.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
