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@ARTICLE{Jonard:844042,
      author       = {Jonard, François and Bircher, Simone and Demontoux,
                      François and Weihermüller, Lutz and Razafindratsima,
                      Stephen and Wigneron, Jean-Pierre and Vereecken, Harry},
      title        = {{P}assive {L}-{B}and {M}icrowave {R}emote {S}ensing of
                      {O}rganic {S}oil {S}urface {L}ayers: {A} {T}ower-{B}ased
                      {E}xperiment},
      journal      = {Remote sensing},
      volume       = {10},
      number       = {2},
      issn         = {2072-4292},
      address      = {Basel},
      publisher    = {MDPI},
      reportid     = {FZJ-2018-01558},
      pages        = {304 -},
      year         = {2018},
      abstract     = {Organic soils play a key role in global warming because
                      they store large amount of soil carbon which might be
                      degraded with changing soil temperatures or soil water
                      contents. There is thus a strong need to monitor these soils
                      and, in particular, their hydrological characteristics
                      using, for instance, space-borne L-band brightness
                      temperature observations. However, there are still open
                      issues with respect to soil moisture retrieval techniques
                      over organic soils. In view of this, organic soil blocks
                      with their vegetation cover were collected from a heathland
                      in the Skjern River catchment in western Denmark and then
                      transported to a remote sensing field laboratory in Germany
                      where their structure was reconstituted. The controlled
                      conditions at this field laboratory made it possible to
                      perform tower-based L-band radiometer measurements of the
                      soils over a period of two months. Brightness temperature
                      data were inverted using a radiative transfer (RT) model for
                      estimating the time variations in the soil dielectric
                      permittivity and the vegetation optical depth. In addition,
                      the effective vegetation scattering albedo parameter of the
                      RT model was retrieved based on a two-step inversion
                      approach. The remote estimations of the dielectric
                      permittivity were compared to in situ measurements. The
                      results indicated that the radiometer-derived dielectric
                      permittivities were significantly correlated with the in
                      situ measurements, but their values were systematically
                      lower compared to the in situ ones. This could be explained
                      by the difference between the operating frequency of the
                      L-band radiometer (1.4 GHz) and that of the in situ sensors
                      (70 MHz). The effective vegetation scattering albedo
                      parameter was found to be polarization dependent. While the
                      scattering effect within the vegetation could be neglected
                      at horizontal polarization, it was found to be important at
                      vertical polarization. The vegetation optical depth
                      estimated values over time oscillated between 0.10 and 0.19
                      with a mean value of 0.13. This study provides further
                      insights into the characterization of the L-band brightness
                      temperature signatures of organic soil surface layers and,
                      in particular, into the parametrization of the RT model for
                      these specific soils. Therefore, the results of this study
                      are expected to improve the performance of space-borne
                      remote sensing soil moisture products over areas dominated
                      by organic soils.},
      cin          = {IBG-3},
      ddc          = {620},
      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)16},
      UT           = {WOS:000427542100148},
      doi          = {10.3390/rs10020304},
      url          = {https://juser.fz-juelich.de/record/844042},
}