| Volumes and Issues Contents of Issue 2 |
www.biogeosciences-discuss.net/6/4059/2009/
doi:10.5194/bgd-6-4059-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Modelling LAI at a regional scale with ISBA-A-gs: comparison with satellite-derived LAI over southwestern France
1CNRM/GAME (Météo-France, CNRS), Toulouse, France
2LSCE (CEA, CNRS), Gif-sur-Yvette, France
3Unité de Recherche sur l'Ecosystème Prairial (INRA), Clermont-Ferrand, France
*now at: CESBIO (UPS, CNRS, IRD, CNES), Toulouse, France
**now at: Department of Civil and Environmental Engineering, The University of Melbourne, Melbourne, Australia
Abstract. A CO2-responsive land surface model (the ISBA-A-gs model of Météo-France) is used to simulate photosynthesis and Leaf Area Index (LAI) in southwestern France for a 3-year period (2001–2003). A domain of about 170 000 km2 is covered at a spatial resolution of 8 km. The capability of ISBA-A-gs to reproduce the seasonal and the inter-annual variability of LAI at a regional scale, is assessed with two satellite-derived LAI products. One originates from the CYCLOPES programme using SPOT/VEGETATION data, and the second is based on MODIS data. The comparison reveals discrepancies between the two satellite LAI estimates and between satellite and simulated LAI values, both in their intensity and in the timing of the leaf onset. The model simulates higher LAI values for the C3 crops and coniferous trees than the satellite observations, which may be due to a saturation effect within the satellite signal. The simulated leaf onset presents a significant delay for mountainous grasslands. In-situ observations at a mid-altitude grassland site show that the generic temperature response of photosynthesis used in the model is not appropriate for plants adapted to the cold climatic conditions of the mountainous areas. This study demonstrates the potential of LAI remote sensing products for identifying and locating models' shortcomings at a regional scale.
Discussion Paper (PDF, 4739 KB) Interactive Discussion (Closed, 6 Comments) Final Revised Paper (BG)
Citation: Brut, A., Rüdiger, C., Lafont, S., Roujean, J.-L., Calvet, J.-C., Jarlan, L., Gibelin, A.-L., Albergel, C., Le Moigne, P., Soussana, J.-F., and Klumpp, K.: Modelling LAI at a regional scale with ISBA-A-gs: comparison with satellite-derived LAI over southwestern France, Biogeosciences Discuss., 6, 4059-4093, doi:10.5194/bgd-6-4059-2009, 2009. Bibtex EndNote Reference Manager XML
