Preprints
https://doi.org/10.5194/egusphere-2023-2731
https://doi.org/10.5194/egusphere-2023-2731
13 Dec 2023
 | 13 Dec 2023
Status: this preprint is open for discussion.

Layer-optimized SAR processing with a mobile phase-sensitive radar for detecting the deep englacial stratigraphy of Colle Gnifetti, Switzerland/Italy

Falk M. Oraschewski, Inka Koch, M. Reza Ershadi, Jonathan Hawkins, Olaf Eisen, and Reinhard Drews

Abstract. Radio-echo sounding is a standard technique for imaging the englacial stratigraphy of glaciers and ice sheets. In most cases, internal reflection horizons (IRHs) represent former glacier surfaces and comprise information about past accumulation, ice deformation and allow to link ice core chronologies. IRHs in the lower third of the ice column are often difficult to detect or coherently trace. In the polar ice sheets, progress in IRH detection has been made by using multistatic, phase-coherent radars, enabling synthetic-aperture radar (SAR) processing. However, these radar systems are often not suitable for deployment on mountain glaciers. We present a proof-of-concept study for a lightweight, phase-coherent, and ground-based radar system, based on the phase-sensitive radio echo-sounder (pRES). To improve the detectability of IRHs we additionally adapted a layer-optimized SAR (LO-SAR) processing scheme to this setup. We showcase the system capability at Colle Gnifetti, Switzerland/Italy, and detect significantly deeper and older IRHs compared to previously deployed pulsed radar systems. Continuous IRHs are now apparent down to the base of the glacier. Corresponding reflection mechanisms for this glacier are linked to a stratified acidic impurity which was deposited at a higher rate due to increased industrial activity in the area. Possible improvements of the system are discussed. If successfully implemented, these may provide a new way to map the deep internal structure of Colle Gnifetti and other mountain glaciers more extensively in future deployments.

Falk M. Oraschewski, Inka Koch, M. Reza Ershadi, Jonathan Hawkins, Olaf Eisen, and Reinhard Drews

Status: open (until 28 Feb 2024)

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  • RC1: 'Comment on egusphere-2023-2731', Anonymous Referee #1, 07 Feb 2024 reply
  • RC2: 'Comment on egusphere-2023-2731', Benjamin Hills, 21 Feb 2024 reply
Falk M. Oraschewski, Inka Koch, M. Reza Ershadi, Jonathan Hawkins, Olaf Eisen, and Reinhard Drews
Falk M. Oraschewski, Inka Koch, M. Reza Ershadi, Jonathan Hawkins, Olaf Eisen, and Reinhard Drews

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Short summary
Mountain glaciers have a layered structure which contains information about past snow accumulation and ice flow. Using ground-looking radar instruments, the internal structure can be observed to obtain this information. In the deeper parts of the glacier, detecting layers is often difficult. In this study we present a new approach to observe deep englacial layers in an Alpine glacier (Colle Gnifetti, Switzerland/Italy) and investigate why these deeper layers are harder to detect at this site.