Estimativas de evapotranspiração e as conseqüências devido aos erros na determinação de saldo de radiação e efeitos advectivos

Oliveira, Gertrudes Macário de; Leitão, Mário de Miranda Vilas Boas Ramos

doi:10.1590/s1415-43662000000300007

Cited by 8 publications

(6 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…3 and Table 3 refer only to the daytime period (Rnet-G > 0). When considering Rnet values for a 24 h period, the error associated with the LE calculation and the evapotranspiration estimation and, consequently, the correct application in irrigation water depth can reach 2.2 MJ.m -2 .day -1 (Oliveira and Leitão, 2000). The same procedures are applied to other components of energy balance.…”

Section: Resultsmentioning

confidence: 99%

“…This equation does not consider some components, such as the energy stored in the tree canopies and the energy used in the photosynthetic process, due to its little representation in relation to the net radiation (Rnet), and the difficulty of its acquisition (Borges et al, 2008), respectively. The analysis of the energy balance was performed considering only the daytime (Rnet-G > 0) since it represents the most accurate way and with smallest error in studies related to energy and evapotranspiration balance (Oliveira and Leitão, 2000).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Diurnal Energy Balance in a Mango Orchard in the Northeast of Pará, Brazil

Souza

Rodrigues

Sousa

et al. 2018

Rev. bras. meteorol.

View full text Add to dashboard Cite

This study aimed to evaluate the diurnal energy balance during the reproductive stage of two growing seasons of a mango orchard in the northeast of Pará, Brazil. Therefore, a micrometeorological tower was installed and instrumented, in the center of the experimental area, to monitor meteorological variables, besides the phenological evaluation of the mango orchard, which was carried out during growing seasons of 2010-2011 (October 2010 to January 2011) and of 2011-2012 (September 2011 to January 2012). The energy balance was obtained by the bowen ration technique, and the available energy partitioned into heat flux to the ground, sensible heat and latent heat. The amount of rainfall was crucial to the partition of the net radiation in the energy balance components. It provided the variation in the consumption of available energy between 69% and 78% as latent heat flux, and between 23% and 32% as sensible heat flux. The heat flux to the ground was small, representing less than 1% of the net radiation, showing that the mango orchard exhibits good soil cover preventing large variations in soil heating.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Diurnal Energy Balance in a Mango Orchard in the Northeast of Pará, Brazil

Souza

Rodrigues

Sousa

et al. 2018

Rev. bras. meteorol.

View full text Add to dashboard Cite

show abstract

“…Significant errors can be made in estimating the ET when Rn is not correctly measured or estimated, with differences of as much as 2.2 MJ·m −2 ·day −1 [45]. In the present study, when we analyzed the different cloud cover conditions, we found that the MRE for Rn estimated was 0.2 -5.1 MJ·m −2 ·day −1 for clear sky days, 0.01 -3.5 MJ·m −2 ·day −1 for days with scattered clouds, 0.4 -3.1 MJ·m −2 ·day −1 for days with broken clouds and 1.3 -2.7 MJ·m −2 ·day −1 for overcast days ( Table 4).…”

Section: Resultsmentioning

confidence: 99%

Estimation of Evapotranspiration by Various Net Radiation Estimation Formulae for Non-Irrigated Grass in Brazil

Cunha

Schöffel²,

Volpe³

2014

JWARP

View full text Add to dashboard Cite

The objective of this study was to assess the accuracy of estimating evapotranspiration (ET) using the FAO-56 Penman-Monteith (FAO-56-PM) model, with measured and estimated net radiation (Rnmeasured and Rnestimated, respectively), the latter obtained via five different models. We used meteorological data collected between August 2005 and June 2008, on a daily basis and on a seasonal basis (wet vs. dry seasons). The following data were collected: temperature; relative humidity; global global solar radiation (Rs); wind speed and soil heat flux. The atmospheric pressure was determined by aneroid barograph, and sunshine duration was quantified with a Campbell-Stokes recorder. In addition to the sensor readings (Rnmeasured), five different models were used in order to obtain the Rnestimated. Four of those models consider the effects of cloud cover: the original Brunt model; the FAO-24 model for wet climates; the FAO-24 model for dry climates, and the FAO-56 model. The fifth was a linear regression model based on Rs. In estimating the daily ET0 with the FAO-56-PM model, Rnmeasured can be replaced by Rnestimated, in accordance with the FAO-24 model for dry climates, with a relative error of 2.9%, or with the FAO-56 model, with an error of 4.9%, when Rs is measured, regardless of the season. The Rnestimated obtained with the fifth model has a relatively high error. The original Brunt model and FAO-24 model for wet climates performed more poorly than did the other models in estimating the Rn and ET0. In overcast conditions, the original Brunt model, the FAO-24 model for wet climates, the FAO-24 model for dry climates, the FAO-56 model and the model of linear regression with Rs as the predictor variable tended to overestimate Rn and ET, those estimates becoming progressively more accurate as the cloud cover diminished.

show abstract

“…Contudo, o cálculo dos fluxos pelo método do balanço de energia depende da determinação correta da razão de Bowen, sendo afetada pela precisão e exatidão das medições de temperatura e umidade do ar acima da cultura (Perez et al, 1999;Oliveira & Leitão, 2000;Inman-Bamber & Mcglinchey, 2003).…”

Section: Introductionunclassified

Disponibilidade energética para a cultura da cana-de-açúcar nos tabuleiros costeiros do estado da Paraíba

Azevedo¹,

Saboya²,

Neto³

et al. 2014

Rev. bras. eng. agríc. ambient.

View full text Add to dashboard Cite

R E S U M OUm experimento foi conduzido com a cultivar de cana-de-açúcar (Saccharum spp.) RB92579, no período de 2010 a 2011 em Capim, PB, tendo como objetivo a análise dos componentes dos balanços de radiação e energia. Monitoraram-se as variáveis: radiação solar incidente e refletida; saldo de radiação; radiação atmosférica incidente à superfície, radiação efetiva emitida e o albedo da superfície vegetada. O balanço de energia, fundamentado na razão de Bowen, foi utilizado na determinação dos fluxos de calor latente e sensível para o ar e o solo. Para as fases de crescimento máximo e maturação observou-se que: a) não houve mudanças significativas no comportamento dos componentes do balanço de radiação; b) o albedo variou de 0,17 a 0,27 com média de 0,23; c) as regressões lineares entre o saldo de radiação e o saldo de radiação de ondas curtas apresentaram elevados níveis de correlação; d) o coeficiente térmico diminuiu e o coeficiente de transformação em ondas longas aumentou com o aumento da cobertura vegetal; e) o saldo de radiação diário e os fluxos de calor latente e sensível aumentaram do período chuvoso para o período seco e f) 82% do saldo de radiação foram utilizados como calor latente, 16% como calor sensível para aquecimento do ar e 2% como calor sensível para aquecimento do solo. Availability of energy for sugarcane in the coastal plains of Paraíba state A B S T R A C TAn experiment was conducted with the sugarcane (Saccharum spp.) variety RB92579, during the period of 2010 to 2011 in Capim,PB, aiming to analyse the components of the radiation and energy balances. The following variables were monitored: incident and reflected solar radiation, net radiation, atmospheric radiation incident to the surface, emitted effective radiation and the albedo of the vegetated surface. The energy balance based on the Bowen ratio was used to determine the latent and air and soil sensible heat fluxes. For the sugarcane maximum growth and maturation phases showed that: a) there were no significant changes in the behavior of the radiation balance components, b) the albedo ranged from 0.17 to 0.27 with an average of 0.23; c) the linear regressions between net radiation and net shortwave radiation showed high levels of correlation; d) the thermal coefficient decreased while the coefficient of transformation into long waves increased with increasing vegetation cover, e) the daily net radiation and the latent and sensible heat fluxes increased from the rainy to the dry seasons; f) 82% of net radiation was used as latent heat, 16% and 2% as sensible heat for heating air and the soil, respectively.

show abstract

Estimativas de evapotranspiração e as conseqüências devido aos erros na determinação de saldo de radiação e efeitos advectivos

Cited by 8 publications

References 9 publications

Diurnal Energy Balance in a Mango Orchard in the Northeast of Pará, Brazil

Diurnal Energy Balance in a Mango Orchard in the Northeast of Pará, Brazil

Estimation of Evapotranspiration by Various Net Radiation Estimation Formulae for Non-Irrigated Grass in Brazil

Disponibilidade energética para a cultura da cana-de-açúcar nos tabuleiros costeiros do estado da Paraíba

Contact Info

Product

Resources

About