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Communications at congresses:
On the use of GPR energetic reflection coefficients in glaciological applications.
Year:2009
Research Areas
  • Geophysics
Information
Abstract
In this paper we analyse the suitability of Ground-Penetrating Radar (GPR) energetic reflection coefficients for glaciological applications, with focus on glacier hydrology. Standard coefficients such as the internal reflection power (IRP) and bedrock reflection power (BRP), or normalised versions of them, are first analysed in order to point out their weaknesses. Alternative versions of them, such as the internal reflection energy (IRE) or the bedrock reflection maximum (BRM), or normalised versions of them, are then introduced, aimed at overcoming the weaknesses of the standard definitions. Examples are shown using field data from radiophysical investigations made at Hansbreen, a polythermal glacier in Spitsbergen, in July-August 2003 and in April 2004. These investigations, aimed at studying the glacier hydrology, included repeated radar profiling (20 and 25 MHz) along a transverse profile, repeated common midpoint measurements, continuous radar measurements during 8 days at a fixed site, meteorological observations, and continuous ice surface velocity monitoring by differential GPS. The repeated GPR profiles are interpreted in terms of variations in the amount of water at the ice-bed interface, and also in terms of variations of melting at the ice surface, which decreases the power transmitted into the ice. The spatial variations of the internal reflection coefficients correlate with the changes in thickness of the cold ice layer and the occurrence of a drainage and crevasse systems. The comparison of internal and bedrock coefficients allow us to suggest different styles of hydraulic connection of either isolated crevasses, or complex moulin and crevasse systems, with the underlying bedrock. A good hydraulic connection between surface and bed seems to be responsible for the increase in basal sliding, and thus surface velocity, immediately following high surface melting events.
International
Si
Congress
European Geosciences Union Annual Meeting 2009
960
Place
Vienna, Austria,
Reviewers
Si
ISBN/ISSN
1029-7006
Start Date
19/04/2009
End Date
24/04/2009
From page
1
To page
1
Geophysical Research Abstracts, Vol. 11, EGU2009-9804, 2009. ISBN/ISSN: 1029-7006.
Participants
  • Autor: Francisco Jose Navarro Valero (UPM)
  • Autor: Javier Jesus Lapazaran Izargain (UPM)
  • Autor: Jaime Otero Garcia (UPM)
Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: Grupo de Simulación Numérica en Ciencias e Ingeniería
  • Departamento: Matemática Aplicada a las Tecnologías de la Información
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