@article{fdi:010042494,
  title = {{I}mprovement of {FAO}-56 method for olive orchards through sequential assimilation of thermal infrared-based estimates of {ET}},
  author = {{E}r {R}aki, {S}. and {C}hehbouni, {A}bdelghani and {H}oedjes, {J}. and {E}zzahar, {J}. and {D}uchemin, {B}eno{\^i}t and {J}acob, {F}r{\'e}d{\'e}ric},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he aim of this study is to use the {FAO}-56-based single crop coefficient approach to estimate actual evapotranspiration ({AET}) of an olive ({O}lea europaea {L}.) orchard in the {M}editerranean semi arid region of {T}ensift-basin (central {M}orocco) during two consecutive growing seasons (2003 and 2004). {T}he results showed that using crop coefficients {K}-c suggested by {FAO}-56 method yielded an {AET} overestimation by about 18% when compared against eddy covariance measurements. {T}herefore, the determination of appropriate {K}c values is required to accurately estimate crop water requirement of olive orchards in such water scarce area. {I}n this study, after applying the {K}c values derived over olive orchard in {S}pain by {P}astor and {O}rgaz [{P}astor, {M}., {O}rgaz, {F}., 1994. {R}iego deficitario del olivar: los programas de recorte de riego en olivar. {A}gricultura 746, 768-776 (in {S}panish)], a better agreement was observed between measured and simulated {AET}. {T}he root mean square error ({RMSE}) was reduced by about 28%, from 0.80 to 0.61 mm/day for 2003 and from 0.93 to 0.69 mm/day for 2004. {T}he used {K}c values of olives at three crop growth stages (initial, mid-season and maturity) were 0.65, 0.45, and 0.65, respectively, the mid-season stage value being considerably lower than that suggested by the {FAO}-56. {D}espite these improvements in the performance of {AET} simulations, some discrepancies between measured and simulated {AET} remained, especially when water stress occurred. {T}hese discrepancies were ascribed to the estimation of the stress coefficient {K}-c {T}o overcome this problem, we assimilated into {FAO}-56 single source model estimates of {AET} derived from a simple energy balance model along with thermal infrared observations. {T}he latter were collected with the {ASTER} sensor in 2003 and from ground-based measurements in 2004. {T}he results showed a clear improvement for {FAO}-56 performances after assimilation: for 2003 and 2004, the {RMSE} values between observations and simulations, respectively, dropped down from 0.61 to 0.52 and from 0.69 to 0.46 (corresponding to relative reductions of 15 and 40%, respectively).},
  keywords = {evapotranspiration ; crop coefficient ; {FAO} 56 model ; data assimilation ; {ASTER} ; olea europaea ; semi arid},
  booktitle = {},
  journal = {{A}gricultural {W}ater {M}anagement},
  volume = {95},
  numero = {3},
  pages = {309--321},
  ISSN = {0378-3774},
  year = {2008},
  DOI = {10.1016/j.agwat.2007.10.013},
  URL = {https://www.documentation.ird.fr/hor/fdi:010042494},
}