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Michal Heliasz. Photo.

Michal Heliasz

Research engineer

Michal Heliasz. Photo.

Retrieval and validation of forest background reflectivity from daily Moderate Resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF) data across European forests


  • Jan Pisek
  • Angela Erb
  • Lauri Korhonen
  • Tobias Biermann
  • Arnaud Carrara
  • Edoardo Cremonese
  • Matthias Cuntz
  • Silvano Fares
  • Giacomo Gerosa
  • Thomas Grünwald
  • Niklas Hase
  • Michal Heliasz
  • Andreas Ibrom
  • Alexander Knohl
  • Johannes Kobler
  • Bart Kruijt
  • Holger Lange
  • Leena Leppänen
  • Jean-Marc Limousin
  • Francisco Ramon Lopez Serrano
  • Denis Loustau
  • Petr Lukeš
  • Lars Lundin
  • Riccardo Marzuoli
  • Meelis Mölder
  • Leonardo Montagnani
  • Johan Neirynck
  • Matthias Peichl
  • Corinna Rebmann
  • Eva Rubio
  • Margarida Santos-Reis
  • Crystal Schaaf
  • Marius Schmidt
  • Guillaume Simioni
  • Kamel Soudani
  • Caroline Vincke

Summary, in English

Information about forest background reflectance is needed for accurate biophysical parameter retrieval from forest canopies (overstory) with remote sensing. Separating under- and overstory signals would enable more accurate modeling of forest carbon and energy fluxes. We retrieved values of the normalized difference vegetation index (NDVI) of the forest understory with the multi-angular Moderate Resolution Imaging Spectroradiometer (MODIS) bidirectional reflectance distribution function (BRDF)/albedo data (gridded 500 m daily Collection 6 product), using a method originally developed for boreal forests. The forest floor background reflectance estimates from the MODIS data were compared with in situ understory reflectance measurements carried out at an extensive set of forest ecosystem experimental sites across Europe. The reflectance estimates from MODIS data were, hence, tested across diverse forest conditions and phenological phases during the growing season to examine their applicability for ecosystems other than boreal forests. Here we report that the method can deliver good retrievals, especially over different forest types with open canopies (low foliage cover). The performance of the method was found to be limited over forests with closed canopies (high foliage cover), where the signal from understory becomes too attenuated. The spatial heterogeneity of individual field sites and the limitations and documented quality of the MODIS BRDF product are shown to be important for the correct assessment and validation of the retrievals obtained with remote sensing.


  • Dept of Physical Geography and Ecosystem Science
  • ICOS Sweden

Publishing year












Document type

Journal article


Copernicus GmbH


  • Forest Science
  • Physical Geography




  • ISSN: 1726-4170