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@ARTICLE{Hoven:1005265,
      author       = {Hoven, Dominik and Mester, Achim and Vereecken, Harry and
                      Klotzsche, Anja},
      title        = {{E}valuation of starting model approaches and effective
                      source wavelet variations for high-frequency
                      ground-penetrating radar full-waveform inversion},
      journal      = {Geophysics},
      volume       = {88},
      number       = {2},
      issn         = {0016-8033},
      address      = {Alexandria, Va.},
      publisher    = {GeoScienceWorld},
      reportid     = {FZJ-2023-01392},
      pages        = {KS27 - KS45},
      year         = {2023},
      abstract     = {High-frequency ground-penetrating radar (GPR) full-waveform
                      inversion (FWI) can enhance the characterization of
                      small-scale structures in the subsurface below the decimeter
                      scale. We have investigated the potential and requirements
                      to use FWI for higher-frequency data. Thereby, we focus on
                      the two most important criteria to achieve reliable FWI
                      results: adequate starting models that fulfill the
                      half-wavelength criterion and the accuracy of the effective
                      source wavelet. Therefore, we have defined a realistic
                      reference model, generated synthetic GPR data sets (200,
                      450, and 700 MHz), and tested different standard ray-based
                      starting model methods and frequency-hopping approaches to
                      derive results close to our reference model. Although
                      standard starting models provide good parameter
                      reconstruction for lower-frequency data, a frequency-hopping
                      approach is required for the 700 MHz data. In addition, we
                      have seen that the reconstruction of the conductivity
                      results is more sensitive to the presence of noise (25 dB)
                      than the permittivity tomograms. The definition of the
                      effective source wavelets is directly linked to the accuracy
                      of the starting models; therefore, we investigate the effect
                      on the FWI results for high-frequency data by varying the
                      source wavelets in terms of starting time and/or amplitude.
                      Considering the multiparameter nature of FWI, we observe
                      that time shifts have a greater influence on the performance
                      of the FWI than amplitude variations. Large time shifts of
                      approximately 0.1 ns for the 700 MHz data may lead to the
                      failure of the inversion, whereas amplitude variations
                      $(±5\%$ of the maximum amplitude) affect the quantitative
                      conductivity results only (no effect on permittivity) with
                      an increased root-mean-square error of the data of up to
                      $20\%.$ Using a stochastically perturbed synthetic model, we
                      determine an improved parameter reconstruction for higher
                      frequencies. On the basis of our findings, we develop a
                      workflow to obtain reliable results for high-frequency GPR
                      FWI for future users.},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {2173 - Agro-biogeosystems: controls, feedbacks and impact
                      (POF4-217)},
      pid          = {G:(DE-HGF)POF4-2173},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000983193900005},
      doi          = {10.1190/geo2021-0683.1},
      url          = {https://juser.fz-juelich.de/record/1005265},
}