Efficiency of methods for calculating class A pan coefficients to estimate evapotranspiration reference
The class A pan coefficients (Kp) can be determined with several methods, most based on wind speed, relative humidity and conditions and extension of the border which circles the pan. This study aimed at evaluating the performance of methods used for estimating the Kp, as well as an average and cons...
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| Format: | Article |
| Language: | English |
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Universidade Federal de Goiás
2013-06-01
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| Series: | Pesquisa Agropecuária Tropical |
| Subjects: | |
| Online Access: | https://www.revistas.ufg.br/pat/article/view/18844 |
| _version_ | 1818808285409574912 |
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| author | Paulo César Ribeiro da Cunha Jorge Luiz do Nascimento Pedro Marques da Silveira José Alves Júnior |
| author_facet | Paulo César Ribeiro da Cunha Jorge Luiz do Nascimento Pedro Marques da Silveira José Alves Júnior |
| author_sort | Paulo César Ribeiro da Cunha |
| collection | DOAJ |
| description | The class A pan coefficients (Kp) can be determined with several methods, most based on wind speed, relative humidity and conditions and extension of the border which circles the pan. This study aimed at evaluating the performance of methods used for estimating the Kp, as well as an average and constant Kp (0.70), to evaluate the reference evapotranspiration (ET0) under Brazilian Savannah conditions, in Santo Antônio de Goiás, Goiás State, Brazil. The methods were assessed on an annual basis and during the dry and rainy seasons. The ET0 resulting from the class A pan evaporation, multiplied by the Kp values estimated with the aid of the Doorenbos & Pruitt (1977), Cuenca (1989), Snyder (1992), Pereira et al. (1995) and Allen et al. (1998) methods, were compared with the ET0 estimated by using the Penman-Montheit equation. The coefficients of determination (r2), correlation (r), Willmott index of agreement (d) and performance (c), as well as the mean and maximum absolute errors, were also estimated. Considering the weather conditions during the experiment, the best Kp method to estimate the annual ET0 was the one proposed by Pereira et al. (1995). For the dry season, the method proposed by Cuenca (1989) performed better, while, for the rainy season, all methods showed a low performance, with the Pereira et al. (1995) method being the most efficient one. The use of a constant Kp of 0.70 resulted in a good performance and showed to be a practical option, however, it is necessary to determine it where it will be applied. |
| first_indexed | 2024-12-18T19:39:08Z |
| format | Article |
| id | doaj.art-006ec0c689b44a829a0307b510fc6a64 |
| institution | Directory Open Access Journal |
| issn | 1983-4063 |
| language | English |
| last_indexed | 2024-12-18T19:39:08Z |
| publishDate | 2013-06-01 |
| publisher | Universidade Federal de Goiás |
| record_format | Article |
| series | Pesquisa Agropecuária Tropical |
| spelling | doaj.art-006ec0c689b44a829a0307b510fc6a642022-12-21T20:55:30ZengUniversidade Federal de GoiásPesquisa Agropecuária Tropical1983-40632013-06-0143211412210.1590/S1983-40632013000200005Efficiency of methods for calculating class A pan coefficients to estimate evapotranspiration referencePaulo César Ribeiro da Cunha0Jorge Luiz do Nascimento1Pedro Marques da Silveira2José Alves Júnior3Instituto Federal de Educação, Ciência e Tecnologia Goiano (IFG), Campus Urutaí, Urutaí, GO, Brasil.Universidade Federal de Goiás (UFG), Escola de Agronomia, Goiânia, GO, Brasil.Empresa Brasileira de Pesquisa Agropecuária, Embrapa Arroz e Feijão, Santo Antônio de Goiás, GO, Brasil.Universidade Federal de Goiás (UFG), Escola de Agronomia, Goiânia, GO, Brasil.The class A pan coefficients (Kp) can be determined with several methods, most based on wind speed, relative humidity and conditions and extension of the border which circles the pan. This study aimed at evaluating the performance of methods used for estimating the Kp, as well as an average and constant Kp (0.70), to evaluate the reference evapotranspiration (ET0) under Brazilian Savannah conditions, in Santo Antônio de Goiás, Goiás State, Brazil. The methods were assessed on an annual basis and during the dry and rainy seasons. The ET0 resulting from the class A pan evaporation, multiplied by the Kp values estimated with the aid of the Doorenbos & Pruitt (1977), Cuenca (1989), Snyder (1992), Pereira et al. (1995) and Allen et al. (1998) methods, were compared with the ET0 estimated by using the Penman-Montheit equation. The coefficients of determination (r2), correlation (r), Willmott index of agreement (d) and performance (c), as well as the mean and maximum absolute errors, were also estimated. Considering the weather conditions during the experiment, the best Kp method to estimate the annual ET0 was the one proposed by Pereira et al. (1995). For the dry season, the method proposed by Cuenca (1989) performed better, while, for the rainy season, all methods showed a low performance, with the Pereira et al. (1995) method being the most efficient one. The use of a constant Kp of 0.70 resulted in a good performance and showed to be a practical option, however, it is necessary to determine it where it will be applied.https://www.revistas.ufg.br/pat/article/view/18844Penman-Monteith equationclimateirrigation management |
| spellingShingle | Paulo César Ribeiro da Cunha Jorge Luiz do Nascimento Pedro Marques da Silveira José Alves Júnior Efficiency of methods for calculating class A pan coefficients to estimate evapotranspiration reference Pesquisa Agropecuária Tropical Penman-Monteith equation climate irrigation management |
| title | Efficiency of methods for calculating class A pan coefficients to estimate evapotranspiration reference |
| title_full | Efficiency of methods for calculating class A pan coefficients to estimate evapotranspiration reference |
| title_fullStr | Efficiency of methods for calculating class A pan coefficients to estimate evapotranspiration reference |
| title_full_unstemmed | Efficiency of methods for calculating class A pan coefficients to estimate evapotranspiration reference |
| title_short | Efficiency of methods for calculating class A pan coefficients to estimate evapotranspiration reference |
| title_sort | efficiency of methods for calculating class a pan coefficients to estimate evapotranspiration reference |
| topic | Penman-Monteith equation climate irrigation management |
| url | https://www.revistas.ufg.br/pat/article/view/18844 |
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