English   español  
Por favor, use este identificador para citar o enlazar a este item: http://hdl.handle.net/10261/4325
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Exportar a otros formatos:

A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration

AutorPérez, P. J.; Lecina Brau, Sergio ; Castellví, F.; Martínez-Cob, Antonio ; Villalobos, F. J.
Palabras claveVariable canopy resistance
Penman-Monteith equation
Fecha de publicaciónoct-2006
EditorJohn Wiley & Sons
CitaciónHydrological Processes 20 (3): 515-532 (2006)
ResumenThis paper examines a model for estimating canopy resistance rc and reference evapotranspiration ETo on an hourly basis. The experimental data refer to grass at two sites in Spain with semiarid and windy conditions in a typical Mediterranean climate. Measured hourly ETo values were obtained over grass during a 4 year period between 1997 and 2000 using a weighing lysimeter (Zaragoza, northeastern Spain) and an eddy covariance system (Córdoba, southern Spain). The present model is based on the Penman-Monteith (PM) approach, but incorporates a variable canopy resistance rc as an empirical function of the square root of a climatic resistance r* that depends on climatic variables. Values for the variable rc were also computed according to two other approaches: with the rc variable as a straight-line function of r* (Katerji and Perrier, 1983, Agronomie 3(6): 513-521) and as a mechanistic function of weather variables as proposed by Todorovic (1999, Journal of Irrigation and Drainage Engineering, ASCE 125(5): 235-245). In the proposed model, the results show that rc/ra (where ra is the aerodynamic resistance) presents a dependence on the square root of r*/ra, as the best approach with empirically derived global parameters. When estimating hourly ETo values, we compared the performance of the PM equation using those estimated variable rc values with the PM equation as proposed by the Food and Agriculture Organization, with a constant rc = 70 s m-1. The results confirmed the relative robustness of the PM method with constant rc, but also revealed a tendency to underestimate the measured values when ETo is high. Under the semiarid conditions of the two experimental sites, slightly better estimates of ETo were obtained when an estimated variable rc was used. Although the improvement was limited, the best estimates were provided by the Todorovic and the proposed methods. The proposed approach for rc as a function of the square root of r* may be considered as an alternative for modelling rc, since the results suggest that the global coefficients of this locally calibrated relationship might be generalized to other climatic regions. It may also be useful to incorporate the effects of variable canopy resistances into other climatic and hydrological models.
DescripciónThe definitive version is available at: http://www3.interscience.wiley.com/journal/4125/home
Versión del editorhttp://dx.doi.org/10.1002/hyp.5919
Aparece en las colecciones: (EEAD) Artículos
Ficheros en este ítem:
Fichero Descripción Tamaño Formato  
HyP2006_20_515_532.pdf647,15 kBAdobe PDFVista previa
Mostrar el registro completo

Artículos relacionados:

NOTA: Los ítems de Digital.CSIC están protegidos por copyright, con todos los derechos reservados, a menos que se indique lo contrario.