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Comparison of eight degree-days estimation methods in four agroecological regions in Colombia.

Caicedo, Daniel Rodríguez; Torres, Jose Miguel Cotes and Cure, José Ricardo (2012) Comparison of eight degree-days estimation methods in four agroecological regions in Colombia. [Comparação de oito métodos para calcular graus-dia em quatro regiões agroecológicas.] Bragantia, 71 (2), pp. 299-307.

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Summary

Eight methods were used to estimate degree-days in four Colombian localities. Four methods have been previously proposed in literature: Simple Sine, Double Sine, Simple Triangle, and Double Triangle methods. The other four methods are proposed in this research: Simple Logistic, Double Logistic, Simple Normal, and Double Normal. The estimation of the degree-days through hourly temperature values was used as the reference standard method, and the four localities from where the temperature values were taken were the municipalities of Cajicá (Cundinamarca), Santa Elena (Antioquia), Carepa (Urabá Antioqueño), and Ciudad Bolivar (Zona cafetera Antioqueña). Degree-days obtained by all methods under study were compared through linear regression to those obtained by the reference standard method. There were differences in the correlation of each method to the reference when compared within each region and among regions. The Simple Logistic and Double Logistic methods showed the best performance with acceptable R2 values and considerably lower bias than the other methods. The poorest fit was found in Cajicá, where the average R2 was 0.571. For the regions of Santa Elena and Carepa, the average R2 was 0.756 and 0.733. The best fit was found in Ciudad Bolivar, with an average R2 of 0.826.

Summary translation

Estimativas de graus-dia foram obtidas pelos métodos de seno simples e duplo, triangulo simples e duplo, as quais são amplamente utilizadas. Quatro novos métodos foram propostos e avaliados nesta pesquisa: logística simples e dupla, normal simples e dupla, baseadas em regressão logística e distribuição normal. Registros horários de temperatura obtidos em Cajicá (Cundinamarca), Santa Elena (Antioquia), Carepa (Urabá Antioqueño) e Ciudad Bolivar (Região tradicional da cultura do café) foram utilizados para obter estimativas da soma térmica com maior precisão sendo, portanto, considerada como a referência para comparação utilizando regressão linear. Foram constatadas diferenças entre o ajuste dos métodos dentro de cada região e entre regiões. Foram observados os maiores coeficientes de determinação (R2), nos métodos de logística simples e logística dupla. O menor coeficiente de determinação, de 0,571, foi obtido em Cajicá enquanto nas regiões de Medellín e Carepa, o R2 foi de 0,756 e 0,733 respectivamente. O melhor ajuste foi obtido em Ciudad Bolivar, com um R2 igual a 0,826.

EPrint Type:Journal paper
Keywords:Graus-dia, Tempo térmico, Temperatura basal, Modelagem estatística. Degree-days, Thermal time, Temperature threshold, Statistical modeling.
Agrovoc keywords:
LanguageValueURI
Englishagroecologyhttp://aims.fao.org/aos/agrovoc/c_92381
EnglishStatistical methodshttp://aims.fao.org/aos/agrovoc/c_7377
EnglishTemperaturehttp://aims.fao.org/aos/agrovoc/c_7657
Subjects: Crop husbandry > Production systems
Farming Systems > Farm economics
Farming Systems
Research affiliation: Brazil > Other organizations
ISSN:0006-8705
DOI:10.1590/S0006-87052012005000011
Related Links:http://www.scielo.br/?lng=pt
Deposited By: Baldasso, Heloísa Souza
ID Code:28506
Deposited On:22 Apr 2015 13:44
Last Modified:22 Apr 2015 13:44
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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