Mangiarotti Sylvain, Mazzega P., Hiernaux P., Mougin Eric. (2010). The vegetation cycle in West Africa from AVHRR-NDVI data : horizons of predictability versus spatial scales. Remote Sensing of Environment, 114 (9), p. 2036-2047. ISSN 0034-4257.
Titre du document
The vegetation cycle in West Africa from AVHRR-NDVI data : horizons of predictability versus spatial scales
Année de publication
Mangiarotti Sylvain, Mazzega P., Hiernaux P., Mougin Eric
Remote Sensing of Environment, 2010,
114 (9), p. 2036-2047 ISSN 0034-4257
The predictability of the vegetation cycle is analyzed as a function of the spatial scale over West Africa during the period 1982-2004 The NDVI-AVHRR satellite data time series are spatially aggregated over windows covering a range of sizes from 8 x 8 km(2) to 1024 x 1024 km(2). The times series are then embedded in a low-dimensional pseudo-phase space using a system of time delayed coordinates. The correlation dimension (D-c) and entropy of the underlying vegetation dynamics, as well as the noise level (sigma) are extracted from a nonlinear analysis of the time series The horizon of predictability (H-P) of the vegetation cycle defined as the time interval required for an n% RMS error on the vegetation state to double (i e reach 2n% RMS) is estimated from the entropy production. Compared to full resolution, the intermediate scales of aggregation (in the range of 64 x 64 km(2) to 256 x 256 km(2)) provide times series with a slightly improved signal to noise ratio, longer horizon of predictability (about 2 to 5 decades) and preserve the most salient spatial patterns of the vegetation cycle Insights on the best aggregation scale and on the expected vegetation cycle predictability over West Africa are provided by a set of maps of the correlation dimension (D-c), the horizon of predictability (H-P) and the level of noise (sigma).
Plan de classement
Sciences du milieu 
Etudes, transformation, conservation du milieu naturel