Preprints
https://doi.org/10.5194/tc-2022-181
https://doi.org/10.5194/tc-2022-181
 
19 Sep 2022
19 Sep 2022
Status: this preprint is currently under review for the journal TC.

Spatial characterization of near-surface structure and meltwater runoff conditions across Devon Ice Cap from dual-frequency radar reflectivity

Kristian Chan1, Cyril Grima1, Anja Rutishauser2, Duncan A. Young1, Riley Culberg3, and Donald D. Blankenship1 Kristian Chan et al.
  • 1Institute for Geophysics, University of Texas at Austin, Austin, TX, 78758, USA
  • 2Geological Survey of Denmark and Greenland, Copenhagen, Denmark
  • 3Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA

Abstract. Melting and refreezing processes in the firn of Devon Ice Cap control meltwater infiltration and runoff across the ice cap, but their full spatial extent and effect on near-surface structure is difficult to measure with ground-based traverses or existing satellite remote sensing. Here, we derive the coherent component of the near-surface return from airborne ice-penetrating radar over Devon Ice Cap, Canadian Arctic, to characterize firn containing centimeter to meter-thick ice layers (i.e., ice slabs) formed from refrozen meltwater in firn. Comparison with reflectivities using a thin layer reflectivity model, informed by ground-based radar and firn core measurements, indicate that the coherent component is sensitive to the near-surface firn structure composed of quasi-specular ice and firn layers, limited by the bandwidth-constrained radar range resolution. By leveraging their differences in range resolution, we assess the use of dual-frequency airborne ice-penetrating radar to characterize the spatial and vertical near-surface structure of Devon Ice Cap. Our results suggest that average ice slab thickness throughout the Devon Ice Cap percolation zone ranges from 4.2 to 5.6 m. This implies conditions that can enable lateral meltwater runoff and potentially contribute to the total surface runoff routed through supraglacial rivers down glacier. Together with the incoherent component of the surface return previously studied, our dual-frequency approach provides an alternative method for characterizing bulk firn properties, particularly where ground-based and higher frequency radar data are not available.

Kristian Chan et al.

Status: open (until 14 Nov 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2022-181', Anonymous Referee #1, 25 Sep 2022 reply

Kristian Chan et al.

Kristian Chan et al.

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Short summary
Climate warming has led to more surface meltwater produced on glaciers that can refreeze in firn to form ice layers. Our work evaluates the use of dual-frequency ice-penetrating radar to characterize these ice layers on Devon Ice Cap, Canadian Arctic. Results indicate that they are meters thick and widespread, thus capable of supporting lateral meltwater runoff on top of the ice layer. We find that some of this meltwater runoff could be routed through supraglacial rivers in the ablation zone.