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@ARTICLE{Jonard:21233,
      author       = {Jonard, F. and Weihermüller, L. and Vereecken, H. and
                      Lambot, S.},
      title        = {{A}ccounting for soil surface roughness in the inversion of
                      ultrawideband off-ground {GPR} signal for soil moisture
                      retrieval},
      journal      = {Geophysics},
      volume       = {77},
      issn         = {0016-8033},
      address      = {Tulsa, Okla.},
      publisher    = {SEG},
      reportid     = {PreJuSER-21233},
      pages        = {H1 - H7},
      year         = {2012},
      note         = {This work was supported in part by the Transregional
                      Collaborative Research Centre 32 funded by the DFG (Deutsche
                      Forschungsgemeinschaft) and in part by the FNRS (Fonds
                      National de la Recherche Scientifique, Belgium). The authors
                      are particularly grateful to Khan Zaib Jadoon of the
                      Agrosphere Institute, Forschungszentrum Julich, for his help
                      during the project. Finally, we also thank the anonymous
                      reviewers for their constructive comments.},
      abstract     = {We combined a full-waveform ground-penetrating radar (GPR)
                      model with a roughness model to retrieve surface soil
                      moisture through signal inversion. The proposed approach was
                      validated under laboratory conditions with measurements
                      performed above a sand layer subjected to seven different
                      water contents and four different surface roughness
                      conditions. The radar measurements were performed in the
                      frequency domain in the range of 1-3 GHz and the roughness
                      amplitude standard deviation was varied from 0 to 1 cm. Two
                      inversion strategies were investigated: (1) Full-waveform
                      inversion using the correct model configuration, and (2)
                      inversion focused on the surface reflection only. The
                      roughness model provided a good description of the
                      frequency-dependent roughness effect. For the full-waveform
                      analysis, accounting for roughness permitted us to
                      simultaneously retrieve water content and roughness
                      amplitude. However, in this approach, information on soil
                      layering was assumed to be known. For the surface reflection
                      analysis, which is applicable under field conditions,
                      accounting for roughness only enabled water content to be
                      reconstructed, but with a root mean square error (RMS) in
                      terms of water content of 0.034 m(3) m(-3) compared to an
                      RMS of 0.068 m(3) m(-3) for an analysis where roughness is
                      neglected. However, this inversion strategy required a
                      priori information on soil surface roughness, estimated,
                      e.g., from laser profiler measurements.},
      keywords     = {J (WoSType)},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Geochemistry $\&$ Geophysics},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000300767000019},
      doi          = {10.1190/geo2011-0054.1},
      url          = {https://juser.fz-juelich.de/record/21233},
}