@article{fdi:010060186,
  title = {{C}haracterization of the interannual and intraseasonal variability of {W}est {A}frican vegetation between 1982 and 2002 by means of {NOAA} {AVHRR} {NDVI} data},
  author = {{P}hilippon, {N}. and {J}arlan, {L}ionel and {M}artiny, {N}. and {C}amberlin, {P}. and {M}ougin, {E}ric},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he interannual and intraseasonal variability of {W}est {A}frican vegetation over the period 1982-2002 is studied using the normalized difference vegetation index ({NDVI}) from the {A}dvanced {V}ery {H}igh {R}esolution {R}adiometer ({AVHRR}). {T}he novel independent component analysis ({ICA}) technique is applied to extract the main modes of the interannual variability of the vegetation, among which two modes are worth describing. {T}he first component ({IC}1) describes {NDVI} variability over the {S}ahel from {A}ugust to {O}ctober. {A} strong photosynthetic activity over the {S}ahel is related to above-normal convection and rainfall within the intertropical convergence zone ({ITCZ}) in summertime and is partly associated with colder (warmer) {SST} in the eastern tropical {P}acific (the {M}editerranean). {T}he second component ({IC}2) depicts a dipole pattern between the {S}ahelian and {G}uinean regions during the northern summer followed by a southward-propagating signal from {O}ctober to {D}ecember. {I}t is associated with a north-south dipole in convection and rainfall induced by variations in the latitudinal location of the {ITCZ} as a response to the occurrence of the tropical {A}tlantic dipole. {T}he analysis of the intraseasonal variability of the {S}ahelian vegetation relies on the analysis of the seasonal marches and their main phenological stages. {G}reen-up usually starts in early {J}uly and shows a very low year-to-year variability, while senescence ends by mid-{N}ovember and is prone to larger interannual variability. {S}ix types of vegetative seasonal marches are discriminated according to variations in the timing of phenological stages as well as in the greening intensity. {T}hese types appear to be strongly dependent on rainfall distribution and amount, particularly those recorded in late {A}ugust. {F}inally, year-to-year memory effects are highlighted: {NDVI} recorded during the green-up phase in year j appears to be strongly related to the maximum {NDVI} value recorded at year j - 1.},
  keywords = {{ZONE} {SAHELIENNE} ; {AFRIQUE} {DE} {L}'{OUEST}},
  booktitle = {},
  journal = {{J}ournal of {C}limate},
  volume = {20},
  numero = {7},
  pages = {1202--1218},
  ISSN = {0894-8755},
  year = {2007},
  DOI = {10.1175/{JCLI}4067.1},
  URL = {https://www.documentation.ird.fr/hor/fdi:010060186},
}