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

This 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 gra...

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Autores: Pérez García, Pedro J., Lecina Brau, Sergio, Castellví Sentís, Francesc, Martínez-Cob, Antonio, Villalobos, F. J.
Tipo de recurso: artículo
Estado:Versión aceptada para publicación
Fecha de publicación:2006
País:España
Institución:Universitat de Lleida (UdL)
Repositorio:Repositori Obert UdL
OAI Identifier:oai:repositori.udl.cat:10459.1/65077
Acceso en línea:https://doi.org/10.1002/hyp.5919
http://hdl.handle.net/10459.1/65077
Access Level:acceso abierto
Palabra clave:Variable canopy resistance
Evapotranspiration
Penman-Monteith equation
Grass
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spelling A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspirationPérez García, Pedro J.Lecina Brau, SergioCastellví Sentís, FrancescMartínez-Cob, AntonioVillalobos, F. J.Variable canopy resistanceEvapotranspirationPenman-Monteith equationGrassThis 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.Spanish Ministry of Science and Technology. Grant Number: REN2001‐1630/CLI Department of Universities and Research (Generalitat de Catalunya). Grant Number: 2001SGR‐00306 High Council of Research and Development of the Autonomous Government of AragonWiley2006info:eu-repo/semantics/articleinfo:eu-repo/semantics/acceptedVersionhttps://doi.org/10.1002/hyp.5919http://hdl.handle.net/10459.1/65077reponame:Repositori Obert UdL instname:Universitat de Lleida (UdL)Inglésinfo:eu-repo/grantAgreement/MICYT//REN2001-1630Versió postprint del document publicat a https://doi.org/10.1002/hyp.5919Hydrological Processes, 2006, vol. 20, núm. 3, p. 515-532(c) Wiley, 2006info:eu-repo/semantics/openAccessoai:repositori.udl.cat:10459.1/650772026-06-24T12:42:17Z
dc.title.none.fl_str_mv A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration
title A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration
spellingShingle A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration
Pérez García, Pedro J.
Variable canopy resistance
Evapotranspiration
Penman-Monteith equation
Grass
title_short A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration
title_full A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration
title_fullStr A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration
title_full_unstemmed A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration
title_sort A simple parameterization of bulk canopy resistance from climatic variables for estimating hourly evapotranspiration
dc.creator.none.fl_str_mv Pérez García, Pedro J.
Lecina Brau, Sergio
Castellví Sentís, Francesc
Martínez-Cob, Antonio
Villalobos, F. J.
author Pérez García, Pedro J.
author_facet Pérez García, Pedro J.
Lecina Brau, Sergio
Castellví Sentís, Francesc
Martínez-Cob, Antonio
Villalobos, F. J.
author_role author
author2 Lecina Brau, Sergio
Castellví Sentís, Francesc
Martínez-Cob, Antonio
Villalobos, F. J.
author2_role author
author
author
author
dc.subject.none.fl_str_mv Variable canopy resistance
Evapotranspiration
Penman-Monteith equation
Grass
topic Variable canopy resistance
Evapotranspiration
Penman-Monteith equation
Grass
description This 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.
publishDate 2006
dc.date.none.fl_str_mv 2006
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
format article
status_str acceptedVersion
dc.identifier.none.fl_str_mv https://doi.org/10.1002/hyp.5919
http://hdl.handle.net/10459.1/65077
url https://doi.org/10.1002/hyp.5919
http://hdl.handle.net/10459.1/65077
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv info:eu-repo/grantAgreement/MICYT//REN2001-1630
Versió postprint del document publicat a https://doi.org/10.1002/hyp.5919
Hydrological Processes, 2006, vol. 20, núm. 3, p. 515-532
dc.rights.none.fl_str_mv (c) Wiley, 2006
info:eu-repo/semantics/openAccess
rights_invalid_str_mv (c) Wiley, 2006
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Wiley
publisher.none.fl_str_mv Wiley
dc.source.none.fl_str_mv reponame:Repositori Obert UdL
instname:Universitat de Lleida (UdL)
instname_str Universitat de Lleida (UdL)
reponame_str Repositori Obert UdL
collection Repositori Obert UdL
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,198674

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