The version 3 CYCLOPES algorithms assess the LAI, Fcover, and FAPAR by inversion of the radiative transfer model SAIL (Verhoef, 1984) using neural networks which consider as input the solar zenith angle at 10:00 local time and the normalized nadir reflectances in red, NIR and SWIR wavebands. This method, defined by the CSE team of Inra Avignon, is applied to VEGETATION data. More details on CYCLOPES algorithms can be found in Baret et al.,(2007).

Examples below show the LAI over France, in August 2002 (left) and 2003 (right). The lower values in 2003, compared to those of 2002, result from the strong drought which occured in Western Europe in 2003.

LAI from CYCLOPES project over France in August 2002 (left) and 2003 (right).

LAI, FCover and FAPAR (1999 - 2007) are included in a same product called "Biophysical", which can be downloaded with a readme file. They are provided in tiles of 10°x10° covering the whole globe in plate-carrée projection. The map locating the tiles can be downloaded. A report on the temporal consistency of CYCLOPES products is also available.
Furthermore, LAI, FAPAR, and FCover (1999 - 2003) are extracted over 323 sites of the BELMANIP database (Baret, et al., 2006) used for validation. These extractions covering about 50km*50km can be downloaded, with a list and description of sites.

The CYCLOPES LAI have been validated by comparison with MODIS LAI and in-situ measurements (see below). The results are presented in Weiss et al. (2007).

Time profile of LAI from CYCLOPES and MODIS over a site located in the South-West of France (45.5°N, 1.2°W). The green diamond represents the ground measurement.

Comparison of CYCLOPES and MODIS LAI with ground measurements.

Furthermore, the CYCLOPES LAI participates in a validation exercise of existing global LAI products, coordinated by GSFC/NASA in collaboration with Postel and other product providers. The procedure consists of :
  the intercomparison with LAI products derived in the frame of other projects (MODIS, GLOBCARBON, ECOCLIMAP, CCRS)
  the comparison with in-situ measurements collected over the experimental site of ground networks (VALERI, BIGFOOT,...), and upscaled using high resolution satellite images.

First results have been presented at the Global Land Monitoring Workshop which held in Missoula, from August 8th to 10th, 2006. The whole study, described in Garrigues et al., 2008, concludes that the CYCLOPES LAI displays the best spatio-temporal consistency, and fits the best the ground measurements, in spite of a low LAI level over the densest vegetations.

CYCLOPES LAI is used in the framework of GEOLAND project. Other applications are presented on the CYCLOPES project page.

Baret, F., O. Hagolle, B. Geiger, P. Bicheron, B. Miras, M. Huc, B. Berthelot, f. Nino, M. Weiss, O. Samain, J.L. Roujean, and M. Leroy, LAI, FAPAR, and FCover CYCLOPES global products derived from Vegetation. Part 1 : principles of the algorithm, Remote Sensing of Environment, 110:305-316, 2007.

Baret, F., J.T. Morisette, R.A. Fernandes, J.L.Champeaux, R.B. Myneni, J. Chen, S. Plummer, M. Weiss, C. Bacour, S. Garrigues, and J. Nickeson, Evaluation of the representativeness of Networks of sites for the Global Validation and Intercomparison of Land Biophysical Products : Proposition of the CEOS-BELMANIP, IEEE Transactions on Geoscience and Remote Sensing, vol44, 7, 1794-1803, July 2006.

Garrigues, S., R. Lacaze, F. Baret, J.T. Morisette, M. Weiss, J. Nickeson, R. Fernandes, S. Plummer, N.V. Shabanov, R. Myneni, W. Yang, Validation and Intercomparison of Global Leaf Area Index Products Derived From Remote Sensing Data, Journal of Geophysical Research, 113, G02028, doi:10.1029/2007JG000635, 2008.

Verhoef, W., Light scattering by leaf layers with applications to canopy reflectance modelling : the SAIL model, Remote Sensing of Environment, 16:125-141, 1984.

Weiss, M., F. Baret, S. Garrigues, and R. Lacaze, LAI and FAPAR CYCLOPES global products derived from Vegetation. Part 2 : validation and comparison with MODIS C4 products, Remote Sensing of Environment, 110:317-331, 2007.