Continuous Profiles of Electromagnetic Wave Velocity and Water Content in Glaciers: An Example from Bench Glacier, Alaska, USA
We conducted two-dimensional continuous multi-offset georadar surveys on Bench Glacier, south-central Alaska, USA, to measure the distribution of englacial water. We acquired data with a multichannel 25MHz radar system using transmitter–receiver offsets ranging from 5 to 150 m. We towed the radar sy...
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ftboisestateu:oai:scholarworks.boisestate.edu:cgiss_facpubs-1069 2023-10-29T02:36:28+01:00 Continuous Profiles of Electromagnetic Wave Velocity and Water Content in Glaciers: An Example from Bench Glacier, Alaska, USA Bradford, John Nichols, Joshua Mikesell, T. Dylan Harper, Joel T. 2009-08-01T07:00:00Z https://scholarworks.boisestate.edu/cgiss_facpubs/70 https://doi.org/10.3189/172756409789097540 unknown ScholarWorks https://scholarworks.boisestate.edu/cgiss_facpubs/70 http://dx.doi.org/10.3189/172756409789097540 CGISS Publications and Presentations Geosciences Earth Sciences Geophysics and Seismology text 2009 ftboisestateu https://doi.org/10.3189/172756409789097540 2023-09-29T15:03:39Z We conducted two-dimensional continuous multi-offset georadar surveys on Bench Glacier, south-central Alaska, USA, to measure the distribution of englacial water. We acquired data with a multichannel 25MHz radar system using transmitter–receiver offsets ranging from 5 to 150 m. We towed the radar system at 5–10 kmh–1 with a snow machine with transmitter/receiver positions established by geodetic-grade kinematic differentially corrected GPS (nominal 0.5m trace spacing). For radar velocity analyses, we employed reflection tomography in the pre-stack depth-migrated domain to attain an estimated 2% velocity uncertainty when averaged over three to five wavelengths. We estimated water content from the velocity structure using the complex refractive index method equation and use a three-phase model (ice, water, air) that accounts for compression of air bubbles as a function of depth. Our analysis produced laterally continuous profiles of glacier water content over several kilometers. These profiles show a laterally variable, stratified velocity structure with a low-watercontent (~0–0.5%) shallow layer (~20–30 m) underlain by high-water-content (1–2.5%) ice. Text glacier glaciers Alaska Boise State University: Scholar Works Annals of Glaciology 50 51 1 9 |
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Boise State University: Scholar Works |
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topic |
Geosciences Earth Sciences Geophysics and Seismology |
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Geosciences Earth Sciences Geophysics and Seismology Bradford, John Nichols, Joshua Mikesell, T. Dylan Harper, Joel T. Continuous Profiles of Electromagnetic Wave Velocity and Water Content in Glaciers: An Example from Bench Glacier, Alaska, USA |
topic_facet |
Geosciences Earth Sciences Geophysics and Seismology |
description |
We conducted two-dimensional continuous multi-offset georadar surveys on Bench Glacier, south-central Alaska, USA, to measure the distribution of englacial water. We acquired data with a multichannel 25MHz radar system using transmitter–receiver offsets ranging from 5 to 150 m. We towed the radar system at 5–10 kmh–1 with a snow machine with transmitter/receiver positions established by geodetic-grade kinematic differentially corrected GPS (nominal 0.5m trace spacing). For radar velocity analyses, we employed reflection tomography in the pre-stack depth-migrated domain to attain an estimated 2% velocity uncertainty when averaged over three to five wavelengths. We estimated water content from the velocity structure using the complex refractive index method equation and use a three-phase model (ice, water, air) that accounts for compression of air bubbles as a function of depth. Our analysis produced laterally continuous profiles of glacier water content over several kilometers. These profiles show a laterally variable, stratified velocity structure with a low-watercontent (~0–0.5%) shallow layer (~20–30 m) underlain by high-water-content (1–2.5%) ice. |
format |
Text |
author |
Bradford, John Nichols, Joshua Mikesell, T. Dylan Harper, Joel T. |
author_facet |
Bradford, John Nichols, Joshua Mikesell, T. Dylan Harper, Joel T. |
author_sort |
Bradford, John |
title |
Continuous Profiles of Electromagnetic Wave Velocity and Water Content in Glaciers: An Example from Bench Glacier, Alaska, USA |
title_short |
Continuous Profiles of Electromagnetic Wave Velocity and Water Content in Glaciers: An Example from Bench Glacier, Alaska, USA |
title_full |
Continuous Profiles of Electromagnetic Wave Velocity and Water Content in Glaciers: An Example from Bench Glacier, Alaska, USA |
title_fullStr |
Continuous Profiles of Electromagnetic Wave Velocity and Water Content in Glaciers: An Example from Bench Glacier, Alaska, USA |
title_full_unstemmed |
Continuous Profiles of Electromagnetic Wave Velocity and Water Content in Glaciers: An Example from Bench Glacier, Alaska, USA |
title_sort |
continuous profiles of electromagnetic wave velocity and water content in glaciers: an example from bench glacier, alaska, usa |
publisher |
ScholarWorks |
publishDate |
2009 |
url |
https://scholarworks.boisestate.edu/cgiss_facpubs/70 https://doi.org/10.3189/172756409789097540 |
genre |
glacier glaciers Alaska |
genre_facet |
glacier glaciers Alaska |
op_source |
CGISS Publications and Presentations |
op_relation |
https://scholarworks.boisestate.edu/cgiss_facpubs/70 http://dx.doi.org/10.3189/172756409789097540 |
op_doi |
https://doi.org/10.3189/172756409789097540 |
container_title |
Annals of Glaciology |
container_volume |
50 |
container_issue |
51 |
container_start_page |
1 |
op_container_end_page |
9 |
_version_ |
1781060416148865024 |