Removal of ‘strip noise’ in airborne radio-echo sounding data using combined wavelet and 2D DFT filtering
File(s)
Author(s)
Type
Journal Article
Abstract
Radio-echo sounding (RES) can be used to understand ice-sheet processes, englacial flow structures and bed properties, making it one of the most popular tools in glaciological exploration. However, RES data are often subject to ‘strip noise’, caused by internal instrument noise and interference, and/or external environmental interference, which can hamper measurementand interpretation. For example, strip noise can result in reduced power from the bed, affecting the quality of ice thickness measurements and the characterization of subglacial conditions. Here, we present a method for removing strip noise based on combined wavelet and 2D Fourier filtering. First, we implement discrete wavelet decomposition on RES data to obtain multi-scale wavelet components. Then, 2D DFT spectral analysis is performed on components containing the noise. In the Fourier domain, the 2D DFT spectrum of strip noise keeps its linear features and can be removed with a ‘targeted masking’ operation. Finally, inverse wavelet transforms are performed on all wavelet components, including strip-removed components, to restore the data with enhanced fidelity. Model tests and field-data processing demonstrate the method removes strip noise well and, incidentally, can remove the strong first reflector from the ice surface, thus drastically improving the general quality of radar data.
Date Issued
2020-04-01
Date Acceptance
2019-02-16
Citation
Annals of Glaciology, 2020, 61 (81), pp.124-134
ISSN
0260-3055
Publisher
Cambridge University Press (CUP)
Start Page
124
End Page
134
Journal / Book Title
Annals of Glaciology
Volume
61
Issue
81
Copyright Statement
© The Author(s) 2019. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.
License URL
Sponsor
Natural Environment Research Council (NERC)
Natural Environment Research Council (NERC)
British Council (UK)
Grant Number
NE/K004956/2
GEOG.RE2356
ICECAP-2
Subjects
0401 Atmospheric Sciences
0404 Geophysics
0406 Physical Geography and Environmental Geoscience
Meteorology & Atmospheric Sciences
Publication Status
Published
Date Publish Online
2019-03-28