Depth-dependent artifacts resulting from ApRES signal clipping

Vaňková, Irena ORCID: https://orcid.org/0000-0003-4351-3781; Nicholls, Keith W. ORCID: https://orcid.org/0000-0002-2188-4509; Xie, Surui; Parizek, Byron R.; Voytenko, Denis; Holland, David M.. 2020 Depth-dependent artifacts resulting from ApRES signal clipping. Annals of Glaciology, 61 (81). 108-113. 10.1017/aog.2020.56

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Abstract/Summary

Several autonomous phase-sensitive radio-echo sounders (ApRES) were deployed at Greenland glaciers to investigate ice deformation. Different attenuation settings were tested and it was observed that, in the presence of clipping of the deramped ApRES signal, each setting produced a different result. Specifically, higher levels of clipping associated with lower attenuation produced an apparent linear increase of diurnal vertical cumulative displacement with depth, and obscured the visibility of the basal reflector in the return amplitude. An example with a synthetic deramped signal confirmed that these types of artifacts result from the introduction of harmonics from square-wave-like features introduced by clipping. Apparent linear increase of vertical displacement with depth occurs when the vertical position of a near-surface internal reflector changes in time. Artifacts in the return amplitude may obscure returns from internal reflectors and the basal reflector, making it difficult to detect thickness evolution of the ice and to correctly estimate vertical velocities. Variations in surface melt during ApRES deployments can substantially modulate the received signal strength on short timescales, and we therefore recommend using higher attenuator settings for deployments in such locations.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1017/aog.2020.56
ISSN:	0260-3055
Additional Keywords:	Glaciological instruments and methods, ground-penetrating radar, ice thickness measurements
Date made live:	16 Sep 2020 09:41 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/528026

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1017/aog.2020.56

ISSN:

0260-3055

Additional Keywords:

Glaciological instruments and methods, ground-penetrating radar, ice thickness measurements

Date made live:

16 Sep 2020 09:41 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/528026