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@ARTICLE{Rosenbaum:9705,
      author       = {Rosenbaum, U. and Huisman, J. A. and Weuthen, A. and
                      Vereecken, H. and Bogena, H. R.},
      title        = {{S}ensor-to-{S}ensor {V}ariability of the {ECH}2{O} {EC}-5,
                      {TE}, and 5{TE} {S}ensors in {D}ielectric {L}iquids},
      journal      = {Vadose zone journal},
      volume       = {9},
      issn         = {1539-1663},
      address      = {Madison, Wis.},
      publisher    = {SSSA},
      reportid     = {PreJuSER-9705},
      pages        = {181 - 186},
      year         = {2010},
      note         = {We gratefully acknowledge the support by the SFB 32
                      "Pattern in Soil-Vegetation-Atmosphere Systems: Monitoring,
                      Modeling and Data Assimilation" funded by the Deutsche
                      Forschungsgemeinschaft (DFG). Jan Vrba, Chair of
                      Electromagnetic Theory, RWTH Aachen University, is thanked
                      for his assistance with the complex dielectric permittivity
                      measurements. Colin Campbell, Decagon Devices, is thanked
                      for information concerning the company calibration of the
                      5TE sensor.},
      abstract     = {Low-budget sensors used in wireless soil water content
                      sensor networks typically show considerable variation.
                      Because of the large number of sensors in sensor network
                      applications, it is not feasible to account for this
                      variability using a calibration between sensor response and
                      soil water content. An alternative approach is to split the
                      calibration into two parts: (i) determination of sensor
                      response-permittivity relationships using standard liquids
                      with a defined reference permittivity, and (ii)
                      site-specific calibration between permittivity and soil
                      water content using a subset of sensors. In this study, we
                      determined sensor response-permittivity relationships for
                      several ECH2O, EC-5, TE, and 5TE sensors by Decagon Devices
                      (Pullman, WA). The objectives of this study were to
                      determine (i) the sensor-to-sensor variability and precision
                      of these sensor types, and ( ii) the increase in accuracy
                      when a sensor-specific calibration is used instead of a
                      single calibration. The results showed that the
                      sensor-to-sensor variability was significantly larger than
                      the measurement noise for each sensor type. When a
                      sensor-specific calibration was used, the RMSE expressed in
                      (equivalent) soil water content ranged from 0.008 cm(3)
                      cm(-3) for the TE sensor to 0.014 cm(3) cm(-3) for the EC-5
                      sensor in a permittivity range between (similar to)2 and 35.
                      When a single calibration was used, the RMSE was higher and
                      ranged from 0.01 cm(3) cm(-3) for the 5TE sensor to 0.02
                      cm(3) cm(-3) for the TE sensor. An improvement in accuracy
                      of nearly 0.01 cm(3) cm(-3) can be reached in the
                      high-permittivity range for each sensor type by calibrating
                      each sensor individually.},
      keywords     = {J (WoSType)},
      cin          = {ICG-4 / JARA-ENERGY},
      ddc          = {550},
      cid          = {I:(DE-Juel1)VDB793 / $I:(DE-82)080011_20140620$},
      pnm          = {Terrestrische Umwelt},
      pid          = {G:(DE-Juel1)FUEK407},
      shelfmark    = {Environmental Sciences / Soil Science / Water Resources},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000274392600019},
      doi          = {10.2136/vzj2009.0036},
      url          = {https://juser.fz-juelich.de/record/9705},
}