The Pruitt and Doorenbos version of the Penman equation developed from Doorenbos J, Pruitt WO () Guidelines for predicting crop water requirements. Doorenbos & Pruitt () introduziram a terminologia “Evapotranspiração de Referência”, ETr, para denominar a perda de água por uma cultura específica. method of Department Irrigation and Drainage, Doorenbos and Pruitt and Doorenbos and Pruitt ();day/night wind ratio = 3, PM=Penman-Monteith ( Smith.

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The grass was clipped whenever necessary to keep its height between 0. In overcast conditions, the original Brunt model, the FAO model for wet climates, the FAO lruitt for dry climates, the FAO 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.

Class A pan coefficients (Kp) to estimate daily reference evapotranspiration (ETo)

The class A pan coefficient Kp has been used to convert pan evaporation ECA to grass-reference evapotranspiration EToan important component in water management of irrigated crops. This fixed value is a simple and practical option to convert ECA in ETo, without the need of weather data as wind speed, relative humidity and temperature. Members of Aboriginal, Torres Strait Islander and Maori communities are advised that this catalogue contains names and images of deceased people.

Most of the methods have shown that Kp value is highly dependent on surrounding conditions and is determined by U, H and F. We will contact you if necessary. The Snyder’s method to determine Kp was the worst to convert ECA into ETo, resulting in the lowest agreement and efficiency and the highest errors. Four of those models consider the effects of cloud cover: Details Collect From S See what’s been added to the collection in the current 1 2 3 4 5 6 weeks months years.

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Reference evapotranspiration ETo was measured with an automatic weighing lysimeter 0. To learn more about Copies Direct watch this short online video. Reference evapotranspiration ETo is an essential component for use in water supply planning and irrigation scheduling Snyder, since the crop evapotranspiration ETc is estimated by ETo multiplied by the crop coefficient Kc.

Collection delivery service resumes on Wednesday 2 January There are several methods to estimate Kp, all of them use mean daily data of wind speed Urelative humidity Hand fetch length F. Food and Agriculture Organization of the United Nations. Catalogue Persistent Identifier https: Can I get a copy?

Robust quantitative techniques for validating pesticide transport models. The objective of this study was to assess the accuracy of estimating evapotranspiration ET using the FAO Penman-Monteith FAOPM model, with dooorenbos and estimated net radiation Rnmeasured and Rnestimated, respectivelythe latter obtained via five different models.

When a constant value of Kp 0.

Kpseveral performance criteria were used including regression analysis, agreement index Dmean absolute error MAEmaximum absolute error MAXEand efficiency EFas suggested by Willmott et al. This fixed value is a practical and simple option to convert ECA into ETo, but this value must be calibrated for each place under different climatic conditions.

Journal of Geophysical Research, Ottawa, v. The use of an arbitrary and constant Kp 0. The estimated values of Kp and the observed Kp, obtained from the relationship between ETo measured in a weighing lysimeter and ECA measured in a class A pan, were compared by regression analysis. Reference evapotranspiration based on Class A pan evaporation. When these Kp values were used to estimate daily ETo Figure 2a good agreement was observed between estimated and measured values of ETo, especially when the Kp was estimated by Eq.

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The values of Kp were calculated prutit the relationship between ETo, from the lysimeter, and ECA, and estimated from the following methods: Field crops — Water requirements. The best Kp methods to estimate ETo were Pereira et al. With these methods, the relationship between measured and estimated ETo showed high accuracy and good precision: According to Villa Nova et al.

However, this value must be calibrated and tested for each place under different climatic conditions. National Library of Australia.

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Includes bibliographical references p. From 25 December to 1 Januarythe Library’s Reading Rooms will be closed and no collection requests will be filled. Further information on the Library’s opening hours is available at: However, the R 2 pruirt, which indicate the precision of the estimates, varied between 0.

Table 2 presents the statistical analysis of ETo estimates using different Kp methods. All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Pruitf License. Evapotranspiration as a function of leaf area index and class Doorenboos pan evaporation. The use of a constant value of Kp showed to be a simple and practical option to convert ECA into ETo, however, this value must be calibrated and tested for different climatic conditions.