Design and deployment of a stationary ice-penetrating radar system

Abstract:

Ice-penetrating radar (IPR) is a popular tool in glaciology, used most commonly for mapping ice depth. Dielectric contrasts between englacial materials, including ice, water, and impurities, allow the detection of internal stratigraphy and some characterization of englacial properties. Here we describe the design and the 2014-2015 deployments of an autonomous stationary ice-penetrating radar system that was tested on a large outlet glacier of the Icefield Ranges of southwest Yukon, Canada. The radar system was deployed within a kilometer of an ice-marginal lake that is dammed by the Kaskawulsh Glacier and drains annually in a subglacial jökulhlaup. It was programmed to perform a series of soundings every few hours and was left unattended over the course of 6 weeks in 2014 and 7 weeks in 2015, while the lake level was monitored with a pressure transducer and time-lapse imagery. The 2014 dataset is characterized by a marked decrease in englacial reflector strength and coherence during the drainage of the ice-dammed lake. We interpret these data as a significant change in englacial saturation associated with the flood. The 2015 dataset post-dates the flood and provides an opportunity to examine more subtle changes in englacial and subglacial properties. Radar mapping in the vicinity of the deployment locations provides context for the time-dependent measurements, also showing significant differences before and after lake drainage.