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@ARTICLE{Mozaffari:877845,
      author       = {Mozaffari, Amirpasha and Klotzsche, Anja and Warren, Craig
                      and He, Guowei and Giannopoulos, Antonios and Vereecken,
                      Harry and van der Kruk, Jan},
      title        = {2.5{D} crosshole {GPR} full-waveform inversion with
                      synthetic and measured data},
      journal      = {Geophysics},
      volume       = {85},
      number       = {4},
      issn         = {1942-2156},
      address      = {Alexandria, Va.},
      publisher    = {GeoScienceWorld},
      reportid     = {FZJ-2020-02469},
      pages        = {H71 - H82},
      year         = {2020},
      abstract     = {Full-waveform inversion (FWI) of cross-borehole
                      ground-penetrating radar (GPR) data is a technique with the
                      potential to investigate subsurface structures. Typical FWI
                      applications transform 3D measurements into a 2D domain via
                      an asymptotic 3D to 2D data transformation, widely known as
                      a Bleistein filter. Despite the broad use of such a
                      transformation, it requires some assumptions that make it
                      prone to errors. Although the existence of the errors is
                      known, previous studies have failed to quantify the
                      inaccuracies introduced on permittivity and electrical
                      conductivity estimation. Based on a comparison of 3D and 2D
                      modeling, errors could reach up to $30\%$ of the original
                      amplitudes in layered structures with high-contrast zones.
                      These inaccuracies can significantly affect the performance
                      of crosshole GPR FWI in estimating permittivity and
                      especially electrical conductivity. We have addressed these
                      potential inaccuracies by introducing a novel 2.5D crosshole
                      GPR FWI that uses a 3D finite-difference time-domain forward
                      solver (gprMax3D). This allows us to model GPR data in 3D,
                      whereas carrying out FWI in the 2D plane. Synthetic results
                      showed that 2.5D crosshole GPR FWI outperformed 2D FWI by
                      achieving higher resolution and lower average errors for
                      permittivity and conductivity models. The average model
                      errors in the whole domain were reduced by approximately
                      $2\%$ for permittivity and conductivity, whereas
                      zone-specific errors in high-contrast layers were reduced by
                      approximately $20\%.$ We verified our approach using
                      crosshole 2.5D FWI measured data, and the results showed
                      good agreement with previous 2D FWI results and geologic
                      studies. Moreover, we analyzed various approaches and found
                      an adequate trade-off between computational complexity and
                      accuracy of the results, i.e., reducing the computational
                      effort while maintaining the superior performance of our
                      2.5D FWI scheme.},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {255 - Terrestrial Systems: From Observation to Prediction
                      (POF3-255)},
      pid          = {G:(DE-HGF)POF3-255},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000583755100020},
      doi          = {10.1190/geo2019-0600.1},
      url          = {https://juser.fz-juelich.de/record/877845},
}