Distribution and character of water in a surge-type glacier revealed by multifrequency and multipolarization ground-penetrating radar

摘要

We have investigated the distribution and character of radar scatterers in the glacier Bakaninbreen, Svalbard, using ground-penetrating radar (GPR). The GPR profiles showed scattering regions with an undulating upper boundary in both along- and across-glacier orientations. The simplest interpretation of such scattering regions would be a layer of randomly distributed scatterers with an undulating upper boundary, underlying a layer without scatterers. We propose an alternative model of scatterer distribution, in which the scatterers are confined to obliquely dipping planes. This model is shown to be able to reproduce the shape of the scattering regions observed in the field data and is consistent with previous observations of dipping thrust features in Bakaninbreen from radar data and in outcrop. Multifrequency profiles (50, 100, and 200 MHz) contained scatterers with similar measured power, indicating that the scatterers have decimeter-scale dimensions. Multipolarized antenna configurations were used to detect a preferred polarization direction for scattered radiation, which was approximately across glacier, suggesting that the scatterers are nonspherical and aligned across glacier. The scatterers are thought to be large water bodies confined to dipping planar features and elongated in the strike orientation of the planes.