Journal Article

PreJuSER-11380

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png A New Vector Waveform Inversion Algorithm for Simultaneous Updating of Conductivity and Permittivity Parameters From Combination Crosshole/Borehole-to-Surface GPR Data

Meles, G. A. ; van der Kruk, J.FZJ* ; Greenhalgh, S. A. ; Ernst, J. R. ; Maurer, H. ; Green, A. G.

2010
IEEE New York, NY

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Please use a persistent id in citations: doi:10.1109/TGRS.2010.2046670

Abstract: We have developed a new full-waveform ground-penetrating radar (GPR) multicomponent inversion scheme for imaging the shallow subsurface using arbitrary recording configurations. It yields significantly higher resolution images than conventional tomographic techniques based on first-arrival times and pulse amplitudes. The inversion is formulated as a non-linear least squares problem in which the misfit between observed and modeled data is minimized. The full-waveform modeling is implemented by means of a finite-difference time-domain solution of Maxwell's equations. We derive here an iterative gradient method in which the steepest descent direction, used to update iteratively the permittivity and conductivity distributions in an optimal way, is found by cross-correlating the forward vector wavefield and the backward-propagated vectorial residual wavefield. The formulation of the solution is given in a very general, albeit compact and elegant, fashion. Each iteration step of our inversion scheme requires several calculations of propagating wavefields. Novel features of the scheme compared to previous full-waveform GPR inversions are as follows: 1) The permittivity and conductivity distributions are updated simultaneously (rather than consecutively) at each iterative step using improved gradient and step length formulations; 2) the scheme is able to exploit the full vector wavefield; and 3) various data sets/survey types (e.g., crosshole and borehole-to-surface) can be individually or jointly inverted. Several synthetic examples involving both homogeneous and layered stochastic background models with embedded anomalous inclusions demonstrate the superiority of the new scheme over previous approaches.

Keyword(s): J ; Crosshole radar (auto) ; dielectric permittivity (auto) ; electrical conductivity (auto) ; finite-difference time-domain (FDTD) methods (auto) ; full-waveform inversion (auto) ; GPR (auto) ; Maxwell's equations (auto) ; simultaneous updating (auto)

Note: Manuscript received July 2, 2009; revised October 23, 2009 and January 15, 2010. Date of publication June 7, 2010; date of current version August 25, 2010. This work was supported by grants from the Swiss Federal Institute of Technology Zurich (ETH Zurich) and the Swiss National Science Foundation.

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Research Program(s):

1. Terrestrische Umwelt (P24)

Appears in the scientific report 2010

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