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Daily reference crop evapotranspiration in the humid environments of Azores islands using reduced data sets: accuracy of FAO-PM temperature and Hargreaves-Samani methods

Published on Oct 1, 2018in Theoretical and Applied Climatology 2.32
· DOI :10.1007/s00704-017-2295-2
Paula Paredes18
Estimated H-index: 18
(University of Lisbon),
J. C. Fontes4
Estimated H-index: 4
(University of the Azores)
+ 1 AuthorsLuis S. Pereira51
Estimated H-index: 51
(University of Lisbon)
Abstract
Reference crop evapotranspiration (ETo) estimations using the FAO Penman-Monteith equation (PM-ETo) require several weather variables that are often not available. Then, ETo may be computed with procedures proposed in FAO56, either using the PM-ETo equation with temperature estimates of actual vapor pressure (e a) and solar radiation (R s), and default wind speed values (u 2), the PMT method, or using the Hargreaves-Samani equation (HS). The accuracy of estimates of daily e a, R s, and u 2 is provided in a companion paper (Paredes et al. 2017) applied to data of 20 locations distributed through eight islands of Azores, thus focusing on humid environments. Both estimation procedures using the PMT method (ETo PMT) and the HS equation (ETo HS) were assessed by statistically comparing their results with those obtained for the PM-ETo with data of the same 20 locations. Results show that both approaches provide for accurate ETo estimations, with RMSE for PMT ranging 0.48–0.73 mm day−1 and for HS varying 0.47–0.86 mm day−1. It was observed that ETo PMT is linearly related with PM-ETo, while non-linearity was observed for ETo HS in weather stations located at high elevation. Impacts of wind were not important for HS but required proper adjustments in the case of PMT. Results show that the PMT approach is more accurate than HS. Moreover, PMT allows the use of observed variables together with estimators of the missing ones, which improves the accuracy of the PMT approach. The preference for the PMT method, fully based upon the PM-ETo equation, is therefore obvious.
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Published on Apr 1, 2019in Agricultural Water Management 3.18
Paula Paredes18
Estimated H-index: 18
(Instituto Superior de Agronomia),
Luis S. Pereira51
Estimated H-index: 51
(Instituto Superior de Agronomia)
Abstract The computation of the reference crop evapotranspiration (ET o ) using the FAO Penman-Monteith equation (PM-ET o ) requires data on maximum and minimum air temperatures (T max , T min ), vapour pressure deficit (VPD), solar radiation (R s ) and wind speed at 2 m height (u 2 ). However, those data are often not available, or data sets may be incomplete or have questionable quality. Various procedures were proposed in FAO56 to overcome these limitations and an abundant literature has been...
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Published on Mar 1, 2019in Journal of Hydrology 3.73
Jalal Shiri30
Estimated H-index: 30
(University of Tabriz)
Abstract Among the reference evapotranspiration ( ET o ) equations, temperature-based and radiation-based equations have been accepted as promising approaches when the available meteorological data are limited. The present paper aimed at assessing this general implication in island environments, which might be generally volatile than the interior/coastal zones. Using data from five island locations of Iran, daily ET o values were calculated by the benchmark FAO-Penman-Monteith (FAO56-PM) model, ...
2 Citations Source Cite
Published on Nov 1, 2018in Agricultural Water Management 3.18
Paula Paredes18
Estimated H-index: 18
(Instituto Politécnico Nacional),
Diogo S. Martins6
Estimated H-index: 6
(Instituto Superior de Agronomia)
+ 2 AuthorsCarlos Pires10
Estimated H-index: 10
(University of Lisbon)
Abstract This study aims at assessing the accuracy of estimating daily grass reference evapotranspiration (PM-ET o ) computed with ERA-Interim reanalysis products, as well as to assess the quality of reanalysis products as predictors of daily maximum and minimum temperature, net radiation, dew point temperature and wind speed, which are used to compute PM-ET o . With this propose, ET o computed from local observations of weather variables in 24 weather stations distributed across Continental Por...
1 Citations Source Cite
Published on Nov 1, 2018in Theoretical and Applied Climatology 2.32
Paula Paredes18
Estimated H-index: 18
(University of Lisbon),
J. C. Fontes4
Estimated H-index: 4
(University of the Azores)
+ 1 AuthorsLuis S. Pereira51
Estimated H-index: 51
(University of Lisbon)
Reference crop evapotranspiration (ETo) estimations using the FAO Penman-Monteith equation (PM-ETo) require a set of weather data including maximum and minimum air temperatures (T max, T min), actual vapor pressure (e a), solar radiation (R s), and wind speed (u 2). However, those data are often not available, or data sets are incomplete due to missing values. A set of procedures were proposed in FAO56 (Allen et al. 1998) to overcome these limitations, and which accuracy for estimating daily ETo...
4 Citations Source Cite