% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Bircher:808931,
      author       = {Bircher, S. and Andreasen, M. and Vuollet, J. and
                      Vehvilainen, J. and Rautiainen, K. and Jonard, Francois and
                      Weihermüller, Lutz and Zakharova, E. and Wigneron, J.-P.
                      and Kerr, Y. H.},
      title        = {{S}oil moisture sensor calibration for organic soil surface
                      layers},
      journal      = {Geoscientific instrumentation, methods and data systems},
      volume       = {5},
      issn         = {2193-0856},
      address      = {Göttingen},
      publisher    = {Copernicus Publ.},
      reportid     = {FZJ-2016-02451},
      pages        = {109-125},
      year         = {2016},
      abstract     = {This paper’s objective is to present generic cali-bration
                      functions for organic surface layers derived for thesoil
                      moisture sensors Decagon ECH2O 5TE and Delta-TThetaProbe
                      ML2x, using material from northern regions,mainly from the
                      Finnish Meteorological Institute’s ArcticResearch Center
                      in Sodankylä and the study area of the Dan-ish Center for
                      Hydrology (HOBE). For the Decagon 5TEsensor such a function
                      is currently not reported in the lit-erature. Data were
                      compared with measurements from un-derlying mineral soils
                      including laboratory and field mea-surements. Shrinkage and
                      charring during drying were con-sidered. For both sensors
                      all field and lab data showed con-sistent trends. For
                      mineral layers with low soil organic mat-ter (SOM) content
                      the validity of the manufacturer’s calibra-tions was
                      demonstrated. Deviating sensor outputs in organicand mineral
                      horizons were identified. For the Decagon 5TE,apparent
                      relative permittivities at a given moisture contentdecreased
                      for increased SOM content, which was attributedto an
                      increase of bound water in organic materials with
                      largespecific surface areas compared to the studied mineral
                      soils.ThetaProbe measurements from organic horizons
                      showedstronger nonlinearity in the sensor response and
                      signal satu-ration in the high-level data. The derived
                      calibration fit func-tions between sensor response and
                      volumetric water contenthold for samples spanning a wide
                      range of humus types withdiffering SOM characteristics. This
                      strengthens confidencein their validity under various
                      conditions, rendering them highly suitable for large-scale
                      applications in remote sensingand land surface modeling
                      studies. Agreement between in-dependent Decagon 5TE and
                      ThetaProbe time series from anorganic surface layer at the
                      Sodankylä site was significantlyimproved when the
                      here-proposed fit functions were used.Decagon 5TE data also
                      well-reflected precipitation events.Thus, Decagon 5TE
                      network data from organic surface lay-ers at the Sodankylä
                      and HOBE sites are based on the here-proposed natural log
                      fit. The newly derived ThetaProbe fitfunctions should be
                      used for hand-held applications only,but prove to be of
                      value for the acquisition of instantaneouslarge-scale soil
                      moisture estimates.},
      cin          = {IBG-3},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IBG-3-20101118},
      pnm          = {255 - Terrestrial Systems: From Observation to Prediction
                      (POF3-255) / EXPEER - Distributed Infrastructure for
                      EXPErimentation in Ecosystem Research (262060)},
      pid          = {G:(DE-HGF)POF3-255 / G:(EU-Grant)262060},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000378207600010},
      doi          = {10.5194/gi-5-109-2016},
      url          = {https://juser.fz-juelich.de/record/808931},
}