Desempenho do método de Penman modificado por equação proposta de estimativa do saldo de radiação de ondas longas
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Data
2000-07
Autores
Jesus, Wilson Roberto de [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Comparou-se o desempenho do método de Penman original e Penman modificado com medidas lisimétricas, através de regressão linear. As modificações propostas foram a obtenção de uma equação de estimativa da energia solar de ondas longas Rb, para as condições experimentais. A nova equação para estimativa de Rb foi obtida de forma residual, através da equação de Penman, sendo a evapotranspiração obtida com os dados lisimétricos. Na equação proposta, assim como na original, foram testados diferentes coeficientes da relação entre nebulosidade e razão de insolação. Utilizou-se para análise dados dos anos de 1996 e 1997, sendo 339 dados para gerar o modelo de estimativa de Rb e 366 dados independentes para sua validação. Os resultados no período total demonstraram superestimativas do método de Penman original de 34%. Ao adotar-se como coeficientes da relação entre nebulosidade e insolação, c e d de 0,2 e 0,8, 0,3 e 0,7, houve diminuição das superestimativas sendo b igual a 0,33 e 0,28 respectivamente. A análise por estação do ano apresentou variações no desempenho do método original revelando diminuição de superestimativas no outono e verão quando comparado com o período total sendo o coeficiente angular da regressão linear, b = 0,26. Na primavera e inverno b = 0,44 e 0,47 respectivamente. Em todos eles houve melhora na precisão adotando-se os coeficientes da relação entre nebulosidade e razão de insolação diferentes do proposto no trabalho, demonstrando que, os mesmos não representam as condições climáticas locais. O desempenho do método de Penman utilizando-se a equação proposta para a estimativa de Rb foi de diminuição em 13% quando considerou-se c e d de 0,3 e 0,7, 18% com 0,2 e 0,8 e 23% com 0,1 e 0,9. A análise do método modificado, por estação do ano, revelou que a mesma se mostrou imprópria... .
We compared the performance of original and modified Penman methods with lysimetric measures by linear regression. The suggested alterations were to obtain an estimated equation for Rb long waves solar energy under experimental conditions. This new equation for Rb estimative was attained in residual fashion by Penman equation and evapotranspiration attained by lysimetric data. Diferent realtion coefficient between nebulosity and insolation ratio were tested in both original and proposed ones. The experiment was held at the Agronomy College, Department of Natural Resources, 22o 51’ latitude, 48o 26’ W longitude and 786 m altitude in Botucatu – SP. Analysis from 1996 and 1997 were used, 339 data for Rb estimate model and 336 independent data for validation. Results on the whole period showed superestimative of 34% original Penman method. When c and d and 0,2 and 0,8, 0,3 and 0,9 were used as relating coefficients between nebulosity and insolation there was a decrease in superestimatives were b is equal to 0,33 and 0,28 respectively. Season analysis showed performance variation in original method with a superestimative decrease in autumn and summer when compared with the total period and angular coefficient linear regression as b = 0,26. During spring and winter b = 0,44 and 0,47 respectively. In all of them there was an improvement in precision using relating coefficients between nebulosity and insolation ratio different from the one proposed by the author expressing that they do not show local weather conditions. Penman method performance with the proposed equation for Rb estimative was decreased in 13% when c and d 0,3 and 0,7, 18% with 0,2 and 0,8 and 23% with 0,1 and 0,9 were considered. Modified method analysis by season of the year showed inadequacy in spring and in other seasons showed a surprising superestimative... (Complete abstract, click electronic address below).
We compared the performance of original and modified Penman methods with lysimetric measures by linear regression. The suggested alterations were to obtain an estimated equation for Rb long waves solar energy under experimental conditions. This new equation for Rb estimative was attained in residual fashion by Penman equation and evapotranspiration attained by lysimetric data. Diferent realtion coefficient between nebulosity and insolation ratio were tested in both original and proposed ones. The experiment was held at the Agronomy College, Department of Natural Resources, 22o 51’ latitude, 48o 26’ W longitude and 786 m altitude in Botucatu – SP. Analysis from 1996 and 1997 were used, 339 data for Rb estimate model and 336 independent data for validation. Results on the whole period showed superestimative of 34% original Penman method. When c and d and 0,2 and 0,8, 0,3 and 0,9 were used as relating coefficients between nebulosity and insolation there was a decrease in superestimatives were b is equal to 0,33 and 0,28 respectively. Season analysis showed performance variation in original method with a superestimative decrease in autumn and summer when compared with the total period and angular coefficient linear regression as b = 0,26. During spring and winter b = 0,44 and 0,47 respectively. In all of them there was an improvement in precision using relating coefficients between nebulosity and insolation ratio different from the one proposed by the author expressing that they do not show local weather conditions. Penman method performance with the proposed equation for Rb estimative was decreased in 13% when c and d 0,3 and 0,7, 18% with 0,2 and 0,8 and 23% with 0,1 and 0,9 were considered. Modified method analysis by season of the year showed inadequacy in spring and in other seasons showed a surprising superestimative... (Complete abstract, click electronic address below).
Descrição
Palavras-chave
Radiação, Evapotranspiração
Como citar
JESUS, Wilson Roberto de. Desempenho do método de Penman modificado por equação proposta de estimativa do saldo de radiação de ondas longas. 2000. ix, 59 f. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciências Agronômicas, 2000.