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@PHDTHESIS{Dimitrov:279286,
      author       = {Dimitrov, Marin},
      title        = {{I}nterpretation of {L}-band brightness temperatures of
                      differently tilled bare soil plots},
      volume       = {292},
      school       = {Universität Bonn},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2015-07301},
      isbn         = {978-3-95806-098-2},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {XIV, 116 S.},
      year         = {2015},
      note         = {Universität Bonn, Diss., 2015},
      abstract     = {The structure of the surface soil layer is strongly
                      influenced by soil tillage practices with important
                      consequences for the soil hydraulic properties and soil
                      moisture dynamics in the top soil layer. In this study, an
                      L-band microwave radiometer and an infrared camera were used
                      to monitor bare soil plots with different structure: tilled,
                      seedbed, and compacted plots. The L-band brightness
                      temperatures were calculated from the raw radiometric data
                      using the radiometer effective transmissivity estimated with
                      the described new algorithm for sky calibration. The new
                      calibration algorithm reduces the bias of brightness
                      temperature estimates. Radiative transfer, dielectric
                      mixing, roughness correction, and soil hydrological models
                      were coupled to determine and disentangle soil hydraulic and
                      surface roughness parameters of the bare soil plots from
                      time series of L-band brightness temperatures using inverse
                      modeling. Two soil hydraulic property models were
                      considered: the uni-modal model of Mualem van Genuchten and
                      the bi-modal model of Durner. Microwave radiative transfer
                      was modeled by two different approaches: the Fresnel
                      equation with depth averaged dielectric permittivity of 2 cm
                      or 5 cm thick surface layers, and a coherent radiative
                      transfer model(CRTM) that accounts for vertical gradients in
                      dielectric permittivity. Two global optimization algorithms
                      (DREAMzs and SCE-UA) were implemented to estimate the
                      optimal solution and the posterior distribution of the soil
                      hydraulic and surface roughness parameters. Brightness
                      temperatures simulated by the CRTM and the 2-cm layer
                      Fresnel model fitted well to the measured ones suggesting
                      that L-band brightness temperatures may be linked to the
                      soil moisture in a 2 cm thick surface layer. Differences in
                      absolute and normalized L-band brightness temperatures
                      between the plots reflect the effect of tillage on the soil
                      structure. The inversely estimated surface roughness
                      parameters compared well with those derived from laser
                      profiler measurements. Both the laboratory derived and the
                      retrieved from L-band brightness temperatures water
                      retention curves were bi-modal. In order to validate the
                      inversely retrieved soil hydraulic functions, simulated
                      water contents were compared with insitu measurements and
                      differences in predicted evaporation rates between the plots
                      were compared with differences in measured IR temperatures.
                      Depth specific calibration relations were found to be
                      essential to derive soil moisture from near-to-surface
                      installed sensors. Furthermore, differences in simulated
                      actual evaporation rates between the plots were confirmed by
                      observed differences in measured IR temperatures. The
                      results, presented in this study, indicate that effects of
                      soil management on soil surface roughness and soil hydraulic
                      properties can be inferred from L-band brightness
                      temperatures.},
      cin          = {IBG-3},
      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)11 / PUB:(DE-HGF)3},
      urn          = {urn:nbn:de:0001-2016022922},
      url          = {https://juser.fz-juelich.de/record/279286},
}