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@ARTICLE{Bayat:884846,
      author       = {Bayat, Bagher and Camacho, Fernando and Nickeson, Jaime and
                      Cosh, Michael and Bolten, John and Vereecken, Harry and
                      Montzka, Carsten},
      title        = {{T}oward operational validation systems for global
                      satellite-based terrestrial essential climate variables},
      journal      = {International journal of applied earth observation and
                      geoinformation},
      volume       = {95},
      issn         = {0303-2434},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {FZJ-2020-03283},
      pages        = {102240 -},
      year         = {2020},
      abstract     = {Terrestrial Essential Climate Variables, known as
                      terrestrial ECVs, are key sources of information for both
                      application- and scientific- oriented research. A large
                      number of global terrestrial ECV products have been derived
                      from satellite observations, and more are forthcoming. To
                      unlock the full potential of these products, end-users need
                      to know their uncertainties and error magnitudes. Due to the
                      lack of conformity among validation strategies, a wide range
                      of validation approaches have been employed to assess the
                      quality of these products, and have resulted in reduced
                      comparability even for the same terrestrial ECV. Addressing
                      this challenge in validation practices requires the use of
                      unified, standard, publicly available, traceable and
                      objective validation procedures that are operational for all
                      products of a specific terrestrial ECV, and preferably also
                      applicable for all ECVs at the global scale. This can allow
                      end-users to perform comparative assessments. To this end,
                      the current study aims to investigate the readiness status
                      of a selected group of seven global long-term
                      satellite-based terrestrial ECVs for operational validation.
                      Selected variables are Leaf Area Index (LAI), Land Surface
                      Temperature (LST), Evapotranspiration (ET), Soil Moisture
                      (SM), Albedo, the fraction of Absorbed Photosynthetically
                      Active Radiation (fAPAR), and Land Cover (LC). For each of
                      these terrestrial ECVs, we reviewed key prerequisites and
                      primary tools [notably, long term global product
                      availability, globally distributed in situ measurement
                      availability, a validation good practice protocol, and an
                      online validation platform] required for developing an
                      operational validation system. With respect to the
                      “readiness level”, the investigation results demonstrate
                      that LAI, SM, and LC are at the highest level of readiness
                      for moving toward a full operational validation at the
                      global scale. However, ET is at the lowest level of
                      readiness, mainly due to the lack of standard validation
                      good practice protocol and lack of a pilot online validation
                      platform. The remainder of the selected terrestrial ECVs are
                      identified to be at mid-level readiness, mainly because
                      either a validation platform (i.e., LST and albedo) or good
                      practice protocol (i.e., fAPAR) still needs to be developed.
                      This review can pave the way for open-access, traceable,
                      transparent, and operational validation procedures of
                      satellite-based global terrestrial ECVs.},
      cin          = {IBG-3},
      ddc          = {550},
      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:000601280500003},
      doi          = {10.1016/j.jag.2020.102240},
      url          = {https://juser.fz-juelich.de/record/884846},
}