CYCLOPES

CYCLOPES is a European Union FP5 project, which has benefited also from additional funding from CNES, Région Midi-Pyrénées, and Réseau Terre et Espace.

Coordinated by INRA Avignon, CYCLOPES is fully perfomed in the frame of the POSTEL Thematic Centre. The Expertise Centres define the algorithms :

The Service Centre has developed the operational processing lines, performed the production, and disseminates the products to the scientific community.

CYCLOPES products (normalized surface reflectances, LAI, fAPAR, FCover) are derived from data acquired by the VEGETATION sensor. They have a global spatial coverage with a 1 km resolution. They cover the period 1999-2003 with a time step of 10 days. Years from 2004 to 2006 should be available during the first quarter of 2008. Albedo products are currently under validation at CNRM. 

CYCLOPES LAI and FAPAR have been validated by comparison with MODIS products and with ground measurements. The results are presented in Weiss et al., (2007). Furthermore, CYCLOPES LAI participates in an intercomparison exercice of existing global LAI products (CYCLOPES, ECOCLIMAP, GLOBCARBON, MODIS), coordinated by NASA/GSFC in collaboration with POSTEL and other products providers. First results of this work have been presented at the Global Land Vegetation Monitoring workshop in Missoula (August 8-10, 2006). The full study, described in Garrigues et al., 2008, concludes that the CYCLOPES LAI shows the best spatio-temporal consistency, and compares the best to the spatialized ground measurements (figure below) (VALERI, BIGFOOT, etc...), although the LAI level is a little bit low over the densest vegetation.

Scatter plots of CYCLOPES, MODIS, ECOCLIMAP and GLOBCARBON LAI with ground measurements (PNG)

Comparison of CYCLOPES, ECOCLIMAP, GLOBCARBON, and MODIS LAI with spatialized ground measurements collected over various vegetation types : crop (red), grass (orange), Evergreen Needleleaf forest (light green), Evergreen Broadleaf Forest (dark green), and Mixed (ENF+DBF) Forest (magenta) (from Garrigues et al., 2007) .

Users have been identified in the framework of CYCLOPES project to test the usefulness of products for two applications linked to climate change :

  • UCL : detection of land cover change and land use change
  • MPI-Jena and MPI-Hamburg : carbon cyle modelling

Other applications use the CYCLOPES products. As example, we can mention some LTHE activities performed in the frame of AMMA project. The CYCLOPES LAI is one input of the ISBA (Noilhan et Planton, 1989) surface scheme in the C-MEB model (Pellarin et al., 2006a) to simulate the microwave emission of a scene. The simulated Brightness Temperature (TB) is then compared to the TB derived from the AMSR-E sensor (below). The study, which aims to elaborate a regional high resolution mapping of soil moisture, was performed over the Niger (Pellarin et al., 2006b), and can be extended to Benin and Mali.

Comparison of TB simultaed by C-MEB model and measured by AMSR-E sensor over Niger, by Pellarin et al., 2006. (PNG)
Brightness Temperature (TB) simulated by the C-MEB model at 1km resolution (left). Re-gridded to 25km resolution (centre), it is compared to AMSR-E TB (right) (from Pellarin et al., 2006b).




References :

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.Article describing the prinicples of CYCLOPES algorithms, PDF - 870.1 ko
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.Article presenting the intercomparison of global LAI products derived from remote sensing data, PDF - 2.4 Mo
Noilhan, J, and S. Planton, A simple parameterization of land surface processesfor meteorological models, Monthly Weather Review, 117, 536-549, 1989.
Pellarin, T., Y.H. Kerr, J.-P. Wigneron, Global simulation of brightness temperatures at 6.6 and 10.7 Ghz over land based on SMMR data set analysis, IEEE Transactions on Geoscience and Remote Sensing, vol.44, Issue 9, pp 2492-2505, 2006a.
Pellarin, T., J.-M. Cohard, J.-P. Laurent, L. Descroix, High resolution soil moisture mapping using AMSR-E brightness temperatures over the Niger site of the AMMA project, RAQRS Symposium, Valencia, 2006bPoster presenting the use of CYCLOPES LAI as input of C-MEB model to simulate TB over AMMA sites., PDF - 5 Mo
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.Article presenting the results of CYCLOPES products validation by comparison with MODIS products and in-situ measurements., PDF - 1.6 Mo