Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation

Detalhes bibliográficos
Autor(a) principal: Shahidian, Shakib
Data de Publicação: 2014
Outros Autores: Serralheiro, Ricardo Paulo, Serrano, João Ramalho, Teixeira, José Luís
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10174/13254
https://doi.org/10.1080/02626667.2014.938076
Resumo: The purpose of this work is to study the annual patterns in climate parameters and to evaluate how these influence the quality of reference evapotranspiration (ETo) estimates obtained from the Hargreaves Samani (HS) equation, since the method only uses the measured temperature parameter directly. To conclude, the work evaluates how these patterns can be used to improve the HS ETo estimates. Ten year moving averages from a set of CIMIS stations were used to evaluate the relations between solar radiation (Rs), temperature (T) and ETo. The results indicate that T treads behind solar radiation and its value peaks some 25 days later. As a result, the main irrigation season in the Mediterranean climate (May 1-September 30) can be divided into three phases: increasing Rs and T; decreasing Rs with increasing T; decreasing Rs and T. Non univocal annual cycles were observed between Rs and T, ETo and Rs, and ETo and T. These annual patterns result in important seasonal changes in the ratio between the Hargreaves Samani and Penman Monteith (FAO PM) ETo estimates. The changes are particularly important during the irrigation season, where the FAO PM initially calculates greater ETo values than the HS methodology and from the end of May to early September, the HS equation overestimates the ETo values. The total overestimation by the HS equation during this period is 17 mm, or 3%. These patterns obtained from 2000-2009 data were used to calibrate and improve HS ETo estimates at new sites during the 2010-2011 period. Calibration based on the proposed seasonal region-wide FAO PM/ HS ETo ratios improved both the bias, which decreased from 0.40 to 0.36 mm day −1, and r2, which increased from 0.67 to 0.87 of the ETo estimates during the irrigation season. The proposed methodology can be easily applied to other regions, even when the existing weather stations are sparse.
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spelling Seasonal climate patterns and their influence on calibration of the Hargreaves Samani EquationHargreaves SamaniEvapotranspirationClimateirrigationThe purpose of this work is to study the annual patterns in climate parameters and to evaluate how these influence the quality of reference evapotranspiration (ETo) estimates obtained from the Hargreaves Samani (HS) equation, since the method only uses the measured temperature parameter directly. To conclude, the work evaluates how these patterns can be used to improve the HS ETo estimates. Ten year moving averages from a set of CIMIS stations were used to evaluate the relations between solar radiation (Rs), temperature (T) and ETo. The results indicate that T treads behind solar radiation and its value peaks some 25 days later. As a result, the main irrigation season in the Mediterranean climate (May 1-September 30) can be divided into three phases: increasing Rs and T; decreasing Rs with increasing T; decreasing Rs and T. Non univocal annual cycles were observed between Rs and T, ETo and Rs, and ETo and T. These annual patterns result in important seasonal changes in the ratio between the Hargreaves Samani and Penman Monteith (FAO PM) ETo estimates. The changes are particularly important during the irrigation season, where the FAO PM initially calculates greater ETo values than the HS methodology and from the end of May to early September, the HS equation overestimates the ETo values. The total overestimation by the HS equation during this period is 17 mm, or 3%. These patterns obtained from 2000-2009 data were used to calibrate and improve HS ETo estimates at new sites during the 2010-2011 period. Calibration based on the proposed seasonal region-wide FAO PM/ HS ETo ratios improved both the bias, which decreased from 0.40 to 0.36 mm day −1, and r2, which increased from 0.67 to 0.87 of the ETo estimates during the irrigation season. The proposed methodology can be easily applied to other regions, even when the existing weather stations are sparse.Hydrological Sciences Journal2015-03-11T17:30:06Z2015-03-112014-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articlehttp://hdl.handle.net/10174/13254http://hdl.handle.net/10174/13254https://doi.org/10.1080/02626667.2014.938076engShahidian, S., Serralheiro, R. P., Serrano, J. R., & Teixeira, J. L. (2014). Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation. Hydrological Sciences Journal, (just-accepted).DOI: 10.1080/02626667.2014.938076ERUshakib@uevora.ptricardo@uevora.ptjrms@uevora.ptjlteixeira@isa.utl.pt214Shahidian, ShakibSerralheiro, Ricardo PauloSerrano, João RamalhoTeixeira, José Luísinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-01-03T18:58:32Zoai:dspace.uevora.pt:10174/13254Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T01:06:40.894921Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation
title Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation
spellingShingle Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation
Shahidian, Shakib
Hargreaves Samani
Evapotranspiration
Climate
irrigation
title_short Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation
title_full Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation
title_fullStr Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation
title_full_unstemmed Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation
title_sort Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation
author Shahidian, Shakib
author_facet Shahidian, Shakib
Serralheiro, Ricardo Paulo
Serrano, João Ramalho
Teixeira, José Luís
author_role author
author2 Serralheiro, Ricardo Paulo
Serrano, João Ramalho
Teixeira, José Luís
author2_role author
author
author
dc.contributor.author.fl_str_mv Shahidian, Shakib
Serralheiro, Ricardo Paulo
Serrano, João Ramalho
Teixeira, José Luís
dc.subject.por.fl_str_mv Hargreaves Samani
Evapotranspiration
Climate
irrigation
topic Hargreaves Samani
Evapotranspiration
Climate
irrigation
description The purpose of this work is to study the annual patterns in climate parameters and to evaluate how these influence the quality of reference evapotranspiration (ETo) estimates obtained from the Hargreaves Samani (HS) equation, since the method only uses the measured temperature parameter directly. To conclude, the work evaluates how these patterns can be used to improve the HS ETo estimates. Ten year moving averages from a set of CIMIS stations were used to evaluate the relations between solar radiation (Rs), temperature (T) and ETo. The results indicate that T treads behind solar radiation and its value peaks some 25 days later. As a result, the main irrigation season in the Mediterranean climate (May 1-September 30) can be divided into three phases: increasing Rs and T; decreasing Rs with increasing T; decreasing Rs and T. Non univocal annual cycles were observed between Rs and T, ETo and Rs, and ETo and T. These annual patterns result in important seasonal changes in the ratio between the Hargreaves Samani and Penman Monteith (FAO PM) ETo estimates. The changes are particularly important during the irrigation season, where the FAO PM initially calculates greater ETo values than the HS methodology and from the end of May to early September, the HS equation overestimates the ETo values. The total overestimation by the HS equation during this period is 17 mm, or 3%. These patterns obtained from 2000-2009 data were used to calibrate and improve HS ETo estimates at new sites during the 2010-2011 period. Calibration based on the proposed seasonal region-wide FAO PM/ HS ETo ratios improved both the bias, which decreased from 0.40 to 0.36 mm day −1, and r2, which increased from 0.67 to 0.87 of the ETo estimates during the irrigation season. The proposed methodology can be easily applied to other regions, even when the existing weather stations are sparse.
publishDate 2014
dc.date.none.fl_str_mv 2014-01-01T00:00:00Z
2015-03-11T17:30:06Z
2015-03-11
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10174/13254
http://hdl.handle.net/10174/13254
https://doi.org/10.1080/02626667.2014.938076
url http://hdl.handle.net/10174/13254
https://doi.org/10.1080/02626667.2014.938076
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv Shahidian, S., Serralheiro, R. P., Serrano, J. R., & Teixeira, J. L. (2014). Seasonal climate patterns and their influence on calibration of the Hargreaves Samani Equation. Hydrological Sciences Journal, (just-accepted).DOI: 10.1080/02626667.2014.938076
ERU
shakib@uevora.pt
ricardo@uevora.pt
jrms@uevora.pt
jlteixeira@isa.utl.pt
214
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv Hydrological Sciences Journal
publisher.none.fl_str_mv Hydrological Sciences Journal
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str RCAAP
institution RCAAP
reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
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