Lhomme Jean-Paul auteur aut IRD Montes C. auteur aut IRD Jacob Frédéric auteur aut IRD Prevot L. auteur aut IRD text journalArticle eng text/pdf born digital access Evaporation from heterogeneous and sparse canopies is often represented by multi-source models that take the form of electrical analogues based upon resistance networks. The chosen representation de facto imposes a specific form on the composition of elementary fluxes and resistances. The two- and three-source representations are discussed in relation to previous work where some ambiguities arise. Using the two-layer model (Shuttleworth and Wallace, Q J R Meteorol Soc 111:839-855, 1985) and the clumped (three-source) model (Brenner and Incoll, Agric For Meteorol 84:187-205, 1997) as a basis, it is shown that the stomatal characteristics of the foliage (amphistomatous or hypostomatous) generate different formulations. New generic and more concise equations, valid in both configurations, are derived. The differences between the patch and layer approaches are outlined and the consequences they have on the composition and formulation of component fluxes are specified. Then, the issue of calculating the effective resistances of the single-layer model from multi-source representations is addressed. Finally, a sensitivity analysis is carried out to illustrate the significance of the new formulations. specialized Big leaf model Effective parameters Evaporation Heterogeneous and sparse vegetation Multi-layer models 072 020 144 2 243-262 2012 0006-8314 https://www.documentation.ird.fr/hor/fdi:010055997 10.1007/s10546-012-9713-x 0006-8314 [F B010055997] https://www.documentation.ird.fr/hor/fdi:010055997 https://www.documentation.ird.fr/intranet/publi/2012/07/010055997.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2012-07-24 2022-07-26 fdi:010055997 fre