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Communication incl. Poster: BibTeX citation key:  Grippab
Grippa, M., Mougin, E., Demarez, V., Kergoat, L., Gruhier, C., Hiernaux, P., Baup, F., Larouziere, L., De Rosnay, P., Pellarin, T., Galle, S., Lebel, T., Descroix, L., Zin, I., Peugeot, C., Cappelaere, B., Demarty, J., Boulain, N., Seguis, L., Ottlé, C., Saux-Picart, S. & Zribi, M. 2009. Evaluation of remote sensing products over the AMMA-CATCH observatory in West Africa. Work presented at Third International AMMA Conferenceat Ouagadougou, Burkina Faso.
Added by: Fanny Lefebvre 2010-11-23 17:45:10    Last Edited by: Fanny Lefebvre 2010-11-23 17:46:57
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Categories: General
Creators: Baup, Boulain, Cappelaere, Demarez, Demarty, Descroix, Galle, Grippa, Gruhier, Hiernaux, Kergoat, Larouziere, Lebel, Mougin, Ottlé, Pellarin, Peugeot, De Rosnay, Saux-Picart, Seguis, Zin, Zribi
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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Abstract
The aim of this poster is to present a global picture of the ongoing activities on the validation of remote sensing products over the AMMA-CATCH observatory in West Africa. The observatory consists of three sites - the Gourma site, in Mali, the South-West Niger site and Ouémé catchment site in Benin - on a north-south sampling axis across the 100-1300 mm/annum rainfall gradient of the Sahel, Sudanian and North-Guinean bioclimatic zones.
These sites were more intensively instrumented during the AMMA project to monitor on the one hand the climate forcing, and, on the other hand, the spatio-temporal variability of geophysical surface variables at different spatial scales.
Adequate sampling strategy, combined measurements of different variables and the availability of ancillary data, allow addressing the issue of earth observation product quality in an environment where it is rarely done. Of special interest is the simultaneous evaluation of vegetation, radiation and soil moisture product.
Concerning vegetation, the leaf area index (LAI), the vegetation cover and the Fraction of Absorbed Photosynthetic Active Radiation are evaluated. For the LAI in particular, homogeneous sites have been selected over which tree and herb LAI is estimated using hemispherical images and compared to high- and low- resolution satellite products.
The soil moisture measurement network has been developed to sample the major soil types within the study area and to characterize soil moisture at different scales from local to meso scale. The ground measurements are compared to soil moisture products derived from microwave remote sensing sensors such as the Advanced Microwave Scanning Radiometer and the ENVISAT-Advanced Synthetic Aperture Radar.
Finally, surface albedo products derived from MODIS are compared to the albedo measured by in-situ sensors from automatic weather stations, showing a good agreement regarding both the seasonal and the interannual variability.
Added by: Fanny Lefebvre    Last Edited by: Fanny Lefebvre