Estimation of Spruce Needle-Leaf Chlorophyll Content Based on DART and PARAS Canopy Reflectance Models

Lucia Yáñez-Rausell, Zbyněk Malenovský, Miina Rautiainen, Jan G P W Clevers, Petr Lukeš, Jan Hanuš, Michael E. Schaepman

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Needle-leaf chlorophyll content (Cab) of a Norway spruce stand was estimated from CHRIS-PROBA images using the canopy reflectance simulated by the PROSPECT model coupled with two canopy reflectance models: 1)discrete anisotropic radiative transfer model (DART); and 2)PARAS. The DART model uses a detailed description of the forest scene, whereas PARAS is based on the photon recollision probability theory and uses a simplified forest structural description. Subsequently, statistically significant empirical functions between the optical indices ANCB670-720 and ANMB670-720 and the needle-leaf Cab content were established and then applied to CHRIS-PROBA data. The Cab estimating regressions using ANMB670-720 were more robust than using ANCB670-720 since the latter was more sensitive to LAI, especially in case of PARAS. Comparison between Cab estimates showed strong linear correlations between PARAS and DART retrievals, with a nearly perfect one-to-one fit when using ANMB670-720(slope=1.1,offset=11μg.cm-2)0. Further comparison with Cab estimated from an AISA Eagle image of the same stand showed better results for PARAS (RMSE=2.7μg.cm-2 for ANCB670-720;RMSE=9.5μg.cm-2 for ANMB670-720 than for DART (RMSE=7.5μg.cm-2 for ANCB670-720;RMSE=23μg.cm-2 for ANMB670-720). Although these results show the potential for simpler models like PARAS in estimating needle-leaf Cab from satellite imaging spectroscopy data, further analyses regarding parameterization of radiative transfer models are recommended.

Original languageEnglish
Pages (from-to)1534-1544
Number of pages11
JournalIEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Volume8
Issue number4
DOIs
Publication statusPublished - 1 Apr 2015
MoE publication typeA1 Journal article-refereed

Keywords

  • Chlorophyll a + b estimation
  • CHRIS-PROBA
  • coniferous forest
  • continuum removal
  • discrete anisotropic radiative transfer model (DART)
  • needle-leaf, Norway spruce
  • optical indices
  • PARAS, PROSPECT
  • radiative transfer
  • recollision probability

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