% 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{Meyer:865571,
      author       = {Meyer, Thomas and Jagdhuber, Thomas and Piles, María and
                      Fink, Anita and Grant, Jennifer and Vereecken, Harry and
                      Jonard, François},
      title        = {{E}stimating gravimetric water content of a winter wheat
                      field from {L}-band vegetation optical depth},
      journal      = {Remote sensing},
      volume       = {11},
      number       = {20},
      issn         = {2072-4292},
      address      = {Basel},
      publisher    = {MDPI},
      reportid     = {FZJ-2019-04936},
      pages        = {2353 -},
      year         = {2019},
      abstract     = {A considerable amount of water is stored in vegetation,
                      especially in regions with high precipitation rates.
                      Knowledge of the vegetation water status is essential to
                      monitor changes in ecosystem health and to assess the
                      vegetation influence on the water budget. In this study, we
                      develop and validate an approach to estimate the gravimetric
                      vegetation water content (mg), defined as the amount of
                      water [kg] per wet biomass [kg], based on the attenuation of
                      microwave radiation through vegetation. mg is expected to be
                      more closely related to the actual water status of a plant
                      than the area-based vegetation water content (VWC), which
                      expresses the amount of water [kg] per unit area [m2]. We
                      conducted the study at the field scale over an entire growth
                      cycle of a winter wheat field. Tower-based L-band microwave
                      measurements together with in situ measurements of
                      vegetation properties (i.e., vegetation height, and mg for
                      validation) were performed. The results indicated a strong
                      agreement between the in situ measured and retrieved mg (R2
                      of 0.89), with mean and standard deviation (STD) values of
                      0.55 and 0.26 for the in situ measured mg and 0.57 and 0.19
                      for the retrieved mg, respectively. Phenological changes in
                      crop water content were captured, with the highest values of
                      mg obtained during the growth phase of the vegetation (i.e.,
                      when the water content of the plants and the biomass were
                      increasing) and the lowest values when the vegetation turned
                      fully senescent (i.e., when the water content of the plant
                      was the lowest). Comparing in situ measured mg and VWC, we
                      found their highest agreement with an R2 of 0.95 after
                      flowering (i.e., when the vegetation started to lose water)
                      and their main differences with an R2 of 0.21 during the
                      vegetative growth of the wheat vegetation (i.e., where the
                      mg was constant and VWC increased due to structural changes
                      in vegetation). In addition, we performed a sensitivity
                      analysis on the vegetation volume fraction (δ), an input
                      parameter to the proposed approach which represents the
                      volume percentage of solid plant material in air. This
                      δ-parameter is shown to have a distinct impact on the
                      thermal emission at L-band, but keeping δ constant during
                      the growth cycle of the winter wheat appeared to be valid
                      for these mg retrievals.},
      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:000498395800021},
      doi          = {10.3390/rs11202353},
      url          = {https://juser.fz-juelich.de/record/865571},
}