Formation of RADARSAT backscatter feature and undulating firn stratigraphy at an ice-stream margin
On RADARSAT imagery, the southern margin of the onset zone of Bindschadler Ice Stream,
West Antarctica, manifests a multi-banded feature, with brightness varying across the bands and
oscillating along each band. Ground-based radar profiles across the margin reveal folds in the firn
stratigraphy associated with this pattern and provide evidence for correlation between the depth of
shallow isochrones and the RADARSAT backscatter intensity on each profile, allowing us to interpret the
banded feature for firn-layer geometry in three dimensions. We use a kinematic model of isochrone
depth evolution to show how layer folding and the band expression may result from deformation and
advection in the near-surface flow field at ice-stream margins, even with steady flow. The model predicts
the formation of longitudinally patterned bands when the ice-stream acceleration fluctuates along flow.
Concerted study of the planform and stratigraphy of other RADARSAT-detected features on the ice
sheets may help us understand their origin.