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Evidence for variable grounding-zone and shear-margin basal conditions across Thwaites Glacier, West Antarctica

Dustin M. Schroeder, Cyril Grima and Donald D. Blankenship
Evidence for variable grounding-zone and shear-margin basal conditions across Thwaites Glacier, West Antarctica
Geophysics (January 2016) 81 (1): WA35-WA43

Abstract

Definitive interpretation of ice-sheet basal conditions from radar-sounding data beneath outlet-glacier grounding zones and shear margins can be problematic due to poorly constrained and spatially variable englacial attenuation rates and losses from propagation through a rough ice surface. To correct for spatially variable attenuation rates, we developed a novel radar analysis approach that provided improved empirical attenuation correction by fitting linearly variable attenuation rates along radar-sounding profiles from the ice-sheet interior to the grounding zone. We also corrected for ice-surface propagation losses by using surface echo amplitude distributions to constrain the loss of coherent power for surface reflections and two-way propagation through a rough ice surface. By applying this approach to airborne radar-sounding observations of the Thwaites Glacier catchment in West Antarctica, we produced relative reflectivity profiles, which show grounding-zone basal conditions varying across the Amundsen Sea Embayment. Additionally, these techniques provided improved characterization of basal conditions across shear margins, showing that - contrary to previous interpretations - the eastern shear margin of Thwaites Glacier corresponded to a change in basal conditions consistent with a transition from frozen to thawed bed.


ISSN: 0016-8033
EISSN: 1942-2156
Coden: GPYSA7
Serial Title: Geophysics
Serial Volume: 81
Serial Issue: 1
Title: Evidence for variable grounding-zone and shear-margin basal conditions across Thwaites Glacier, West Antarctica
Affiliation: Jet Propulsion Laboratory, Pasadena, CA, United States
Pages: WA35-WA43
Published: 201601
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 40
Accession Number: 2016-007390
Categories: Applied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch map
S82°00'00" - S76°00'00", W115°00'00" - W95°00'00"
Secondary Affiliation: University of Texas at Austin, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 201604
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