@article{fdi:010048232,
  title = {{T}owards an understanding of coupled physical and biological processes in the cultivated {S}ahel-1. {E}nergy and water},
  author = {{R}amier, {D}avid and {B}oulain, {N}icolas and {C}appelaere, {B}ernard and {T}imouk, {F}ranck and {R}abanit, {M}anon and {L}loyd, {C}. {R}. and {B}oubkraoui, {S}t{\'e}phane and {M}{\'e}tayer, {F}. and {D}escroix, {L}uc and {W}awrzyniak, {V}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}his paper presents an analysis of the coupled cycling of energy and water by semi-arid {S}ahelian surfaces, based on two years of continuous vertical flux measurements from two homogeneous recording stations in the {W}ankama catchment, in the {W}est {N}iger meso-site of the {AMMA} project. {T}he two stations, sited in a millet field and in a semi-natural fallow savanna plot, sample the two dominant land cover types in this area typical of the cultivated {S}ahel. {T}he 2-year study period enables an analysis of seasonal variations over two full wet-dry seasons cycles, characterized by two contrasted rain seasons that allow capturing a part of the interannual variability. {A}ll components of the surface energy budget (four-component radiation budget, soil heat flux and temperature, eddy fluxes) are measured independently, allowing for a quality check through analysis of the energy balance closure. {W}ater cycle monitoring includes rainfall, evapotranspiration (from vapour eddy flux), and soil moisture at six depths. {T}he main modes of observed variability are described, for the various energy and hydrological variables investigated. {R}esults point to the dominant role of water in the energy cycle variability, be it seasonal, interannual, or between land cover types. {R}ainfall is responsible for nearly as much seasonal variations of most energy-related variables as solar forcing. {D}epending on water availability and plant requirements, evapotranspiration pre-empts the energy available from surface forcing radiation, over the other dependent processes (sensible and ground heat, outgoing long wave radiation). {I}n the water budget, pre-emption by evapotranspiration leads to very large variability in soil moisture and in deep percolation, seasonally, interannually, and between vegetation types. {T}he wetter 2006 season produced more evapotranspiration than 2005 from the fallow but not from the millet site, reflecting differences in plant development. {R}ain-season evapotranspiration is nearly always lower at the millet site. {H}igher soil moisture at this site suggests that this difference arises from lower vegetation requirements rather than from lower infiltration/higher runoff. {T}his difference is partly compensated for during the next dry season. {E}ffects of water and vegetation on the energy budget appear to occur more through latent heat than through albedo. {A} large part of albedo variability comes from soil wetting and drying. {P}rior to the onset of monsoon rain, the change in air mass temperature and wind produces, through modulation of sensible heat, a marked chilling effect on the components of the surface energy budget.},
  keywords = {{E}ddy covariance ; {S}urface energy budget ; {H}ydrologic cycle ; {M}illet ; {F}allow savanna ; {S}emi-arid ; {SAHEL} ; {ZONE} {SEMIARIDE}},
  booktitle = {},
  journal = {{J}ournal of {H}ydrology},
  volume = {375},
  numero = {1-2},
  pages = {204--216},
  ISSN = {1879-2707},
  year = {2009},
  DOI = {10.1016/j.jhydrol.2008.12.002},
  URL = {https://www.documentation.ird.fr/hor/fdi:010048232},
}