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@ARTICLE{Vargas:885477,
      author       = {Vargas, Juan Quirós and Bendig, Juliane and Mac Arthur,
                      Alasdair and Burkart, Andreas and Julitta, Tommaso and
                      Maseyk, Kadmiel and Thomas, Rick and Siegmann, Bastian and
                      Rossini, Micol and Celesti, Marco and Schüttemeyer, Dirk
                      and Kraska, Thorsten and Muller, Onno and Rascher, Uwe},
      title        = {{U}nmanned {A}erial {S}ystems ({UAS})-{B}ased {M}ethods for
                      {S}olar {I}nduced {C}hlorophyll {F}luorescence ({SIF})
                      {R}etrieval with {N}on-{I}maging {S}pectrometers: {S}tate of
                      the {A}rt},
      journal      = {Remote sensing},
      volume       = {12},
      number       = {10},
      issn         = {2072-4292},
      address      = {Basel},
      publisher    = {MDPI},
      reportid     = {FZJ-2020-03860},
      pages        = {1624 -},
      year         = {2020},
      abstract     = {Chlorophyll fluorescence (ChlF) information offers a deep
                      insight into the plant physiological status by reason of the
                      close relationship it has with the photosynthetic activity.
                      The unmanned aerial systems (UAS)-based assessment of solar
                      induced ChlF (SIF) using non-imaging spectrometers and
                      radiance-based retrieval methods, has the potential to
                      provide spatio-temporal photosynthetic performance
                      information at field scale. The objective of this manuscript
                      is to report the main advances in the development of
                      UAS-based methods for SIF retrieval with non-imaging
                      spectrometers through the latest scientific contributions,
                      some of which are being developed within the frame of the
                      Training on Remote Sensing for Ecosystem Modelling (TRuStEE)
                      program. Investigations from the Universities of Edinburgh
                      (School of Geosciences) and Tasmania (School of Technology,
                      Environments and Design) are first presented, both sharing
                      the principle of the spectroradiometer optical path
                      bifurcation throughout, the so called ‘Piccolo-Doppio’
                      and ‘AirSIF’ systems, respectively. Furthermore, JB
                      Hyperspectral Devices’ ongoing investigations towards the
                      closest possible characterization of the atmospheric
                      interference suffered by orbital platforms are outlined. The
                      latest approach focuses on the observation of one single
                      ground point across a multiple-kilometer atmosphere vertical
                      column using the high altitude UAS named as AirFloX, mounted
                      on a specifically designed and manufactured fixed wing
                      platform: ‘FloXPlane’. We present technical details and
                      preliminary results obtained from each instrument, a summary
                      of their main characteristics, and finally the remaining
                      challenges and open research questions are addressed. On the
                      basis of the presented findings, the consensus is that SIF
                      can be retrieved from low altitude spectroscopy. However,
                      the UAS-based methods for SIF retrieval still present
                      uncertainties associated with the current sensor
                      characteristics and the spatio-temporal mismatching between
                      aerial and ground measurements, which complicate robust
                      validations. Complementary studies regarding the
                      standardization of calibration methods and the
                      characterization of spectroradiometers and data processing
                      workflows are also required. Moreover, other open research
                      questions such as those related to the implementation of
                      atmospheric correction, bidirectional reflectance
                      distribution function (BRDF) correction, and accurate
                      surface elevation models remain to be addressed},
      cin          = {IBG-2},
      ddc          = {620},
      cid          = {I:(DE-Juel1)IBG-2-20101118},
      pnm          = {582 - Plant Science (POF3-582)},
      pid          = {G:(DE-HGF)POF3-582},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000543394800091},
      doi          = {10.3390/rs12101624},
      url          = {https://juser.fz-juelich.de/record/885477},
}