Removal of ‘strip noise’ in airborne radio-echo sounding data using combined wavelet and 2D DFT filtering

• Main Authors: Wang, B, Sun, B, Jiaxin, W, Greenbaum, J, Jingxue, G, Laura, L, Xiangbin, C, Young, D, Blankenship, D, Siegert, M
• Other Authors: Natural Environment Research Council (NERC), British Council (UK)
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Cambridge University Press (CUP) 2019
• Subjects: 0401 Atmospheric Sciences; 0404 Geophysics; 0406 Physical Geography and Environmental Geoscience; Meteorology & Atmospheric Sciences; Annals of Glaciology; Ice Sheet
• Online Access: http://hdl.handle.net/10044/1/67974

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.