Scaling PRI between coniferous canopy structures

Matti Mõttus, Miina Rautiainen

Research output: Contribution to journalArticleScientificpeer-review

12 Citations (Scopus)


We measured simultaneously the spectral albedo of ten Scots pine shoots and the needles constituting the shoots. Next, we used the spectral information to calculate the photochemical reflectance index (PRI) which allows to retrieve photosynthetic productivity from imaging spectroscopy data. We showed that PRI can be scaled from needle to shoot level using a strictly positive scaling factor. The scaling factor is a function of photon recollision probability and the harmonic mean of needle spectral albedos at the wavelengths used in the index. The method is applicable to other normalized difference indices, as demonstrated here using normalized difference vegetation index (NDVI). At shoot level, both PRI and NDVI depend on the angle between view and illumination directions. This anisotropy, however, is not a direct function of scattering angle.
Original languageEnglish
Article number6494342
Pages (from-to)708-714
JournalIEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Issue number2
Publication statusPublished - 9 Apr 2013
MoE publication typeA1 Journal article-refereed


  • Photochemical reflectance index
  • photon recollision probability
  • Pinus sylvestris
  • Scots pine
  • shoot scattering
  • vegetation structure


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