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Radar attenuation tomography using the centroid frequency downshift method

Journal of Applied Geophysics

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Abstract

A method for tomographically estimating electromagnetic (EM) wave attenuation based on analysis of centroid frequency downshift (CFDS) of impulse radar signals is described and applied to cross-hole radar data. The method is based on a constant-Q model, which assumes a linear frequency dependence of attenuation for EM wave propagation above the transition frequency. The method uses the CFDS to construct the projection function. In comparison with other methods for estimating attenuation, the CFDS method is relatively insensitive to the effects of geometric spreading, instrument response, and antenna coupling and radiation pattern, but requires the data to be broadband so that the frequency shift and variance can be easily measured. The method is well-suited for difference tomography experiments using electrically conductive tracers. The CFDS method was tested using cross-hole radar data collected at the U.S. Geological Survey Fractured Rock Research Site at Mirror Lake, New Hampshire (NH) during a saline-tracer injection experiment. The attenuation-difference tomogram created with the CFDS method outlines the spatial distribution of saline tracer within the tomography plane. ?? 1998 Elsevier Science B.V. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Radar attenuation tomography using the centroid frequency downshift method
Series title:
Journal of Applied Geophysics
Volume
40
Issue:
1-3
Year Published:
1998
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Applied Geophysics
First page:
105
Last page:
116
Number of Pages:
12