The Bowen ratio-energy balance method for estimating latent heat flux of irrigated alfalfa evaluated in a semi-arid, advective environment

Todd, Richard W.; Evett, Steven R.; Howell, Terry A.

doi:10.1016/s0168-1923(00)00139-8

Cited by 177 publications

(109 citation statements)

References 25 publications

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“…Both systems were of the automatic exchange mechanism (AEM) type, with air temperature/relative humidity sensors (THP-1, Radiation and Energy Balance Systems, Seattle, WA, USA) on the arms switching positions every 15 minutes to avoid instrument bias [18]. After switching, the sensors were allowed to equilibrate for 5 minutes, and then took measurements for 10 minutes before switching again.…”

Section: Study Areamentioning

confidence: 99%

SEBAL-A: A Remote Sensing ET Algorithm that Accounts for Advection with Limited Data. Part II: Test for Transferability

et al. 2015

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Because the Surface Energy Balance Algorithm for Land (SEBAL) tends to underestimate ET when there is advection, the model was modified by incorporating an advection component as part of the energy usable for crop evapotranspiration (ET). The modification involved the estimation of advected energy, which required the development of a wind function. In Part I, the modified SEBAL model (SEBAL-A) was developed and validated on well-watered alfalfa of a standard height of 40-60 cm. In this Part II, SEBAL-A was tested on different crops and irrigation treatments in order to determine its performance under varying conditions. The crops used for the transferability test were beans (Phaseolus vulgaris L.), wheat (Triticum aestivum L.) and corn (Zea mays L.). The estimated ET using SEBAL-A was compared to actual ET measured using a Bowen Ratio Energy Balance (BREB) system. Results indicated that SEBAL-A estimated ET fairly well for beans and wheat, only showing some slight underestimation of a Mean Bias Error (MBE) of −0.7 mm·d (10.7%) and NSCE of 0.82. The SEBAL-A model showed less or no improvement on corn that was either water-stressed or at early stages of growth. The errors incurred under these conditions were not due to advection not accounted for but rather were due to the nature of SEBAL and SEBAL-A being single-source energy balance models and, therefore, not performing well over heterogeneous surfaces. Therefore, it was concluded that SEBAL-A could be used on a wide range of crops if they are not water stressed. It is recommended that the SEBAL-A model be further studied to be able to accurately estimate ET under dry and sparse surface conditions.

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Section: Study Areamentioning

confidence: 99%

SEBAL-A: A Remote Sensing ET Algorithm that Accounts for Advection with Limited Data. Part II: Test for Transferability

et al. 2015

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“…The Bowen ratio energy balance method is a widely used micrometeorological method to estimate latent heat fluxes because of its simplicity and robustness [50,51]. At the ground level, it has been applied routinely to estimate latent and sensible heat fluxes for various land surface types, such as water, grassland, crops or forests [52].…”

Section: Modeling Approach (B) "Bowen Ratio"mentioning

confidence: 99%

Diurnal Dynamics of Wheat Evapotranspiration Derived from Ground-Based Thermal Imagery

et al. 2014

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Abstract:The latent heat flux, one of the key components of the surface energy balance, can be inferred from remotely sensed thermal infrared data. However, discrepancies between modeled and observed evapotranspiration are large. Thermal cameras might provide a suitable tool for model evaluation under variable atmospheric conditions. Here, we evaluate the results from the Penman-Monteith, surface energy balance and Bowen ratio approaches, which estimate the diurnal course of latent heat fluxes at a ripe winter wheat stand using measured and modeled temperatures. Under overcast conditions, the models perform similarly, and radiometric image temperatures are linearly correlated with the inverted aerodynamic temperature. During clear sky conditions, the temperature of the wheat ear layer could be used to predict daytime turbulent fluxes (root mean squared error and mean absolute error: 20-35 W·m 9776Errors are dependent on the models' ability to simulate diurnal hysteresis effects and are largest during intermittent clouds, due to the discrepancy between the timing of image capture and the time needed for the leaf-air-temperature gradient to adapt to changes in solar radiation. During such periods, we suggest using modeled surface temperatures for temporal upscaling and the validation of image data.

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“…No entanto, pesquisas que determinaram, simultaneamente, os componentes do balanço de energia e a evapotranspiração do caupi são escassas. O balanço de energia é descrito pela equação 1 (LIMA et al, 2005b;TODD et al, 2000): ).…”

Section: Introductionunclassified

Balanço de energia e evapotranspiração de feijão caupi sob condições de sequeiro

Lima¹,

Antonino²,

Lira³

et al. 2011

Rev. Ciênc. Agron.

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5Resumo -Objetivou-se determinar os componentes do balanço de energia (saldo de radiação, fluxos de calor latente, sensível e no solo), a evapotranspiração (ET) e a eficiência no uso de água (EUA) do feijão caupi cultivado sob condições de sequeiro. O experimento foi conduzido numa área de quatro hectares, localizada no CCA/UFPB, Areia, PB (6 o 58'12" S e 35 o 42'15" O e 620 m), durante o período de 22/07/2003 a 17/10/2003. Para a determinação dos componentes do balanço de energia e da ET utilizou-se o método da razão de Bowen, sendo que para isso foi instalada, no centro da área, uma torre micrometeorológica com sensores para medição da temperatura e da umidade relativa, em dois níveis acima do dossel do caupi, além de sensores para a medição do saldo de radiação, da radiação solar global, do fluxo de calor no solo e da precipitação pluvial. Verificou-se que o valor médio da razão saldo de radiação/radiação global (Rn/Rg) foi de 79%, sendo a Rn utilizada, em média, como 65% no fluxo de calor latente (LE/Rn), 23% como fluxo de calor sensível (H/Rn) e 12% como fluxo de calor no solo (G/Rn). Em relação à evapotranspiração, observou-se que o valor total durante o período experimental foi 330,7 mm e o médio de 3,8 mm dia -1 . A produção do caupi foi de apenas 206,0 kg ha -1 , com uma EUA baixa (0,06 kg m -3 ), a qual se deu, provavelmente, devido ao déficit hídrico ocorrido na fase reprodutiva. Palavras-chave -Relações hídricas. Eficiência no uso de água. Razão de Bowen.Abstract -The objective of this study was to assess the energy balance components (net radiation, latent heat flux, sensible heat flux and soil heat flux), evapotranspiration (ET) and water use efficiency (WUE) of cowpea grown under rainfed conditions. The experiment was conducted in a 4 ha area in the CCA, UFPB, belonging to the Municipality of Areia, PB (6 o 58 ' S, 35 o 41 ' W and 620 m) during the period from July, 22 2003 to October, 17 2003. To determine the energy balance components and ET, it was used the Bowen ratio method, and for that, the area was instrumented with a micrometeorological tower containing sensors for measuring air temperature and relative humidity at two levels above the canopy of cowpea. Measurements of net and global radiation, soil heat flux and rainfall were also made. The average value of the net radiation was 79% of the global solar radiation (Rn/Rg), in which 65% appeared as latent heat flux (LE/Rn), 23% as sensible heat flux (H/Rn) and 12% as soil heat flux (G/Rn). The total and average values for actual evapotranspiration were 330.7 mm and 3.8 mm day -1 , respectively. The production of cowpea was only 206.0 kg ha -1 with low WUE (0.06 kg m -3 ), which occurred probably due to water deficit at reproductive stage.

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The Bowen ratio-energy balance method for estimating latent heat flux of irrigated alfalfa evaluated in a semi-arid, advective environment

Cited by 177 publications

References 25 publications

SEBAL-A: A Remote Sensing ET Algorithm that Accounts for Advection with Limited Data. Part II: Test for Transferability

SEBAL-A: A Remote Sensing ET Algorithm that Accounts for Advection with Limited Data. Part II: Test for Transferability

Diurnal Dynamics of Wheat Evapotranspiration Derived from Ground-Based Thermal Imagery

Balanço de energia e evapotranspiração de feijão caupi sob condições de sequeiro

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