Reanalysis of Polythermal Glacier Thermal Structure Using Radar Diffraction Focusing

dc.contributor.authorDelf, Richard
dc.contributor.authorBingham, Robert G.
dc.contributor.authorCurtis, Andrew
dc.contributor.authorSingh, Satyan
dc.contributor.authorGiannopoulos, Antonios
dc.contributor.authorSchwarz, Benjamin
dc.contributor.authorBorstad, Chris P.
dc.date.accessioned2022-08-30T15:25:51Z
dc.date.available2022-08-30T15:25:51Z
dc.date.issued2022-01
dc.descriptionRichard Delf et al, 2022, Reanalysis of polythermal glacier thermal structure using radar diffraction focussing, Journal of Geophysical Research: Earth Surface, , Citation number, 10.1029/2021JF006382. To view the published open abstract, go to https://doi.org/10.1029/2021JF006382en_US
dc.description.abstractGround-penetrating radar (GPR) is widely used on polythermal glaciers to image bed topography and detect internal scatter due to water inclusions in temperate ice. The glaciological importance of this is twofold: bed topography is a primary component for modeling the long-term evolution of glaciers and ice sheets, and the presence of temperate ice and associated englacial water significantly reduces overall ice viscosity. Englacial water has a direct influence on radar velocity, which can result in incorrect observations of bed topography due to errors in depth conversion. Assessment of radar velocities often requires multi-offset surveys, yet these are logistically challenging and time consuming to acquire, hence techniques to extract velocity from common-offset data are required. We calculate englacial radar velocity from common offset GPR data collected on Von Postbreen, a polythermal glacier in Svalbard. We first separate and enhance the diffracted wavefield by systematically assessing data coherence. We then use the focusing metric of negative entropy to deduce a migration velocity field and produce a velocity model which varies spatially across the glacier. We show that this velocity field successfully differentiates between areas of cold and temperate ice and can detect lateral variations in radar velocity close to the glacier bed. This velocity field results in consistently lower ice depths relative to those derived from a commonly assumed constant velocity, with an average difference of 4.9 ± 2.5% of local ice depth. This indicates that diffraction focusing and velocity estimation are crucial in retrieving correct bed topography in the presence of temperate ice.en_US
dc.identifier.citationDelf, R., Bingham, R. G., Curtis, A., Singh, S., Giannopoulos, A., Schwarz, B., & Borstad, C. P. (2022). Reanalysis of polythermal glacier thermal structure using radar diffraction focusing. Journal of Geophysical Research: Earth Surface, 127, e2021JF006382en_US
dc.identifier.issn2169-9003
dc.identifier.urihttps://scholarworks.montana.edu/handle/1/17017
dc.language.isoen_USen_US
dc.publisherAmerican Geophysical Unionen_US
dc.rightscc-byen_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en_US
dc.subjectglacier thermal structureen_US
dc.titleReanalysis of Polythermal Glacier Thermal Structure Using Radar Diffraction Focusingen_US
dc.typeArticleen_US
mus.citation.extentfirstpage1en_US
mus.citation.extentlastpage19en_US
mus.citation.issue2en_US
mus.citation.journaltitleJournal of Geophysical Research: Earth Surfaceen_US
mus.citation.volume127en_US
mus.data.thumbpage3en_US
mus.identifier.doi10.1029/2021JF006382en_US
mus.relation.collegeCollege of Engineeringen_US
mus.relation.departmentCivil Engineering.en_US
mus.relation.universityMontana State University - Bozemanen_US

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