Title: Uncertainty Estimates for the FAPAR Operational Products Derived from MERIS - Impact of Top-of-Atmosphere Radiance Uncertainties and Validation with Field Data
Authors: GOBRON NADINEPINTY BERNARDTABERNER MALCOLMFABER OlgaMELIN FREDERICROBUSTELLI MonicaSNOEIJ PaulLAVERGNE T.AUSSEDAT O.
Citation: REMOTE SENSING OF ENVIRONMENT vol. 112 p. 1871-1883
Publisher: ELSEVIER SCIENCE INC
Publication Year: 2008
JRC N°: JRC40518
ISSN: 0034-4257
URI: www.elsevier.com/locate.rse
http://publications.jrc.ec.europa.eu/repository/handle/JRC40518
DOI: 10.1016/j.rse.2007.09.011
Type: Articles in Journals
Abstract: This paper discusses the accuracy of the operational Medium Resolution Imaging Spectrometer (MERIS) Level 2 land product which corresponds to the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR). The FAPAR value is estimated from daily MERIS spectral measurements acquired at the top-of-atmosphere, using a physically based approach. The products are operationally available at the reduced spatial resolution, i.e. 1.2 km, and can be computed at the full spatial resolution, i.e. at 300 m, from the top-of-atmosphere MERIS data by using the same algorithm. The quality assessment of the MERIS FAPAR products capitalizes on the availability of five years of data acquired globally. The actual validation exercise is performed in two steps including, first, an analysis of the accuracy of the FAPAR algorithm itself with respect to the spectral measurements uncertainties and, second, with a direct comparison of the FAPAR time series against ground-based estimations as well as similar FAPAR products derived from other optical sensor data. The results indicate that the impact of top-of-atmosphere radiance uncertainties on the operational MERIS FAPAR products accuracy is expected to be at about 5-10 % and the agreement with the ground-based estimates over different canopy types is achieved within+ 0.1.
JRC Institute:Institute for Environment and Sustainability

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