Application of photon recollision probability in coniferous canopy reflectance simulations

Miina Rautiainen*, Pauline Stenberg

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

99 Citations (Scopus)


A new semi-physical forest reflectance model, PARAS, is presented in the paper. PARAS is a simple parameterization model for taking into account the effect of within-shoot scattering on coniferous canopy reflectance. Multiple scattering at the small scale represented by a shoot is a conifer-specific characteristic which causes the spectral signature of coniferous forests to differ from that of broadleaved forests. This has for long led to problems in remote sensing of canopy structural variables in coniferous dominated regions. The PARAS model uses a relationship between photon recollision probability and leaf area index (LAI) for simulating forest reflectance. The recollision probability is a measurable, wavelength independent variable which is defined as the probability with which a photon scattered in the canopy interacts with a phytoelement again. In this study, we present application results using PARAS in simulating reflectance of coniferous forests for approximately 800 Scots pine and Norway spruce dominated stands. The results of this study clearly indicate that a major improvement in simulating canopy reflectance in near-infrared (NIR) is achieved by simply accounting for the within-shoot scattering. In other words, the low NIR reflectance observed in coniferous areas is mainly due to within-shoot scattering. In the red wavelength the effect of within-shoot scattering was not pronounced due to the high level of needle absorption in the red range. To conclude the paper, further application possibilities of the presented parameterization model are discussed.

Original languageEnglish
Pages (from-to)98-107
Number of pages10
JournalRemote Sensing of Environment
Issue number1
Publication statusPublished - 15 May 2005
MoE publication typeA1 Journal article-refereed


  • Clumping
  • LAI
  • Leaf area index
  • Shoot scattering
  • Spectral invariant
  • STAR


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