Dominant patterns of AVHRR NDVI interannual variability over the Sahel and linkages with key climate signals (1982-2003)

Lionel Jarlan (1) , Y. M. Tourre , Éric Mougin (1) , N. Philippon (2) , P. Mazzega (3)

1 CESBIO - Centre d'études spatiales de la biosphère
2 CRC - Centre de Recherches de Climatologie
3 LMTG - Laboratoire des Mécanismes et Transfert en Géologie

The spatio-temporal evolution of Sahelian vegetation is analyzed using the Normalized Difference Vegetation Index (NDVI) obtained from the NOAA/AVHRR sensor (1982-2003). Dominant patterns are identified using rotated EOFs. While the first four modes are associated with specific bio-geo-climatic conditions in space, significant time scales are detected using a multi-tapers method. Three interannual time scales (~6.2-, 4.5- and 3.6-year) are present in the first and third NDVI modes over the western Sahel. A quasi-biennial time scale (~2.6-year) is present in second and fourth NDVI modes over the northeast Sahel. During summer, significant lagged correlations are found between the NDVI second (9-month lag) and third (10-month lag) modes, the meridional Atlantic Sea Surface Temperature (SST) gradient, and the zonal SST gradient in the Indian Ocean. Potential physical linkages and dynamics with known climate fluctuations are discussed.

Domaines: Sciences de la Terre

Lionel Jarlan, Y. M. Tourre, Éric Mougin, N. Philippon, P. Mazzega. Dominant patterns of AVHRR NDVI interannual variability over the Sahel and linkages with key climate signals (1982-2003). Geophysical Research Letters, 2005, 32, pp.04701. ⟨10.1029/2004GL021841⟩. ⟨hal-00318861⟩