A recommendation on standardized surface resistance for hourly calculation of reference ETo by the FAO56 Penman-Monteith method

Allen, Richard G.; Pruitt, William O.; Wright, James L.; Howell, Terry A.; Ventura, Francesc; Snyder, Richard L.; Itenfisu, Daniel; Steduto, Pasquale; Berengena, J.; Yrisarry, Javier Baselga; Smith, Mark; Pereira, L. S.; Raes, Dirk; Perrier, Alain; Alves, Isabel; Walter, Ivan A.; Elliott, Ronald L.

doi:10.1016/j.agwat.2005.03.007

Cited by 525 publications

(317 citation statements)

References 31 publications

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“…Para determinação da evapotranspiração de referência utilizou-se a metodologia proposta por Penman-Monteith, que passou por algumas parametrizações, tais como: resistência estomática de 70 s m -1 e altura da grama fixada em 0,12 m, proposta pelo boletim FAO-56 (Allen et al, 2006); com isto, a equação para obtenção da evapotranspiração de referência foi expressa como: em que ETo é a evapotranspiração de referencia (mm d -1 ); Rn é o saldo de radiação (MJ m -2 d -1 ); G é o fluxo de calor no solo (MJ m -2 d -1 ); T é a temperatura média diária do ar (°C); u 2 é a velocidade do vento média diária a 2 m de altura (m s -1 ); e s é a pressão da saturação do vapor média diária (kPa); e a é a pressão atual de vapor média diária (kPa);  é a declividade da curva de pressão de vapor (kPa°C -1 ); e  é a constante psicrométrica (kPa°C -1 ).…”

Section: Introductionunclassified

Evapotranspiração e coeficiente de cultivo do algodoeiro BRS-200 Marrom, irrigado

Bezerra

Azevedo²,

Silva³

et al. 2010

Rev. bras. eng. agríc. ambient.

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RESUMOExperimento conduzido na Embrapa, em Barbalha, CE, nos anos de 2003 e 2005, objetivou a estimativa da evapotranspiração da cultura e do coeficiente de cultivo do algodoeiro BRS-200 Marrom. Sensores de radiação solar global; saldo de radiação; temperatura do ar (bulbos seco e úmido) e velocidade do vento nos níveis de 0,30 e 1,50 m acima da copa da cultura e fluxo de calor no solo foram instalados e os dados coletados por um sistema automático de aquisição de dados. A evapotranspiração da cultura (ET c ) e a evapotranspiração de referência (ET o

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Section: Introductionunclassified

Evapotranspiração e coeficiente de cultivo do algodoeiro BRS-200 Marrom, irrigado

Bezerra

Azevedo²,

Silva³

et al. 2010

Rev. bras. eng. agríc. ambient.

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“…In evaluating Equation 5, z-d was assumed to be 2 m. The value of z 0 for a cotton canopy with full cover was assumed to be 4 cm based on the results of previous studies [10]. Canopy resistance in Equation 4 was assumed to be 50 s/m, a value considered appropriate for non-stressed crop canopies with complete ground cover [24]. Net radiation in Equation 4 was evaluated from Q s and T a using procedures described by Allen et al [2].…”

Section: Weather Data and Petmentioning

confidence: 99%

Spectral Crop Coefficient Approach for Estimating Daily Crop Water Use

Rajan¹,

Maas²

2014

ARS

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While the amount of water used by a crop can be measured using lysimeters or eddy covariance systems, it is more common to estimate this quantity based on weather data and crop-related factors. Among these approaches, the standard crop coefficient method has gained widespread use. A limitation of the standard crop coefficient approach is that it applies to "standard conditions" that are invariant from field to field. In this article, we describe a method for estimating daily crop water use (CWU) that is specific to individual fields. This method, the "spectral crop coefficient" approach, utilizes a crop coefficient numerically equivalent to the crop ground cover observed in a field using remote sensing. This "spectral crop coefficient" K sp is multiplied by potential evapotranspiration determined from standard weather observations to estimate CWU. We present results from a study involving three farmers' fields in the Texas High Plains in which CWU estimated using the K sp approach is compared to observed values obtained from eddy covariance measurements. Statistical analysis of the results suggests that the K sp approach can produce reasonably accurate estimates of daily CWU under a variety of irrigation strategies from fully irrigated to dryland. These results suggest that the K sp approach could be effectively used in applications such as operational irrigation scheduling, where its field-specific nature could minimize over-irrigation and support water conservation.

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“…In 1998, the Food and Agriculture Organization of the United Nations (FAO) gave a fixed surface resistance at 70 s/m for a crop with a uniform height of 0.12 m (Allen et al, 1998). A further recommendation is to use a surface resistance of 50 s/m for daytime and 200 s/m for night-time (Allen et al, 2006). It is also recognized that surface resistance always varies between 50 s/m and 200 s/m for grass and 100 s/m and 400 s/m for forest (Rana et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Surface resistance calibration for a hydrological model using evapotranspiration retrieved from remote sensing data in Nahe catchment forest area

et al. 2015

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In this paper, a method combining graphical and statistical techniques is proposed for surface resistance calibration in a distributed hydrological model, WaSiM-ETH, by comparing daily evapotranspiration simulated by model WaSiM-ETH with corresponding daily evapotranspiration retrieved from remote sensing images. The study area locates in Nahe catchment (Rhineland-Palatinate, Germany, 4065 km 2 ) forest regions. The remote sensing based observations are available for a very limited number of days but representative for most soil moisture conditions. By setting canopy resistance (rc) at 150 s/m, soil surface resistance (rse) at 250 s/m or at 300 s/m for deciduous forest and setting rc at 300 s/m, rse at 600 s/m or at 650 s/m for pine forest, the model exhibits its best overall performance in space and time. It is also found that with sufficient soil moisture, the model exhibits its best performance in space scale.

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A recommendation on standardized surface resistance for hourly calculation of reference ETo by the FAO56 Penman-Monteith method

Cited by 525 publications

References 31 publications

Evapotranspiração e coeficiente de cultivo do algodoeiro BRS-200 Marrom, irrigado

Evapotranspiração e coeficiente de cultivo do algodoeiro BRS-200 Marrom, irrigado

Spectral Crop Coefficient Approach for Estimating Daily Crop Water Use

Surface resistance calibration for a hydrological model using evapotranspiration retrieved from remote sensing data in Nahe catchment forest area

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