scholarly journals Effect of solar radiation models on evapotranspiration estimation

2016 ◽  
Vol 14 (2) ◽  
pp. 247-255
Author(s):  
Milan Gocic ◽  
Mladen Milanovic ◽  
Slavisa Trajkovic
Keyword(s):  
Water Resources ◽  
Solar Radiation ◽  
Reference Evapotranspiration ◽  
Global Solar Radiation ◽  
Crop Evapotranspiration ◽  
Climatic Parameters ◽  
Evapotranspiration Estimation

The crop evapotranspiration has the great effect on defining and planning of water resources. The estimation of evapotranspiration depends on various climatic parameters. In this study, the analysis of the effect of solar radiation (Rs) on daily reference evapotranspiration (ET0) was conducted. The FAO-56 Penman-Monteith method (FAO-56 PM) was used for the estimation of ET0 in Serbia at eight meteorological stations for the period 1980-2010. The Rs was estimated using the ten one-parameter global solar radiation models. The ET0 with Almorox and Hontoria model 1 had the smallest deviation related to the ET0 with Angstr?m-Prescott (AP) model, and ET0 with To?rul et al. model 2 and Rietveld model had the greatest deviation from ET0 with AP model.

scholarly journals Performance of different methods for reference evapotranspiration estimation in Jaíba, Brazil

2018 ◽  
Vol 22 (2) ◽  
pp. 83-89 ◽  
Author(s):  
Gustavo H. da Silva ◽  
Santos H. B. Dias ◽  
Lucas B. Ferreira ◽  
Jannaylton É. O. Santos ◽  
Fernando F. da Cunha
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Standard Method ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Air Humidity ◽  
Method Performance ◽  
Relative Air Humidity ◽  
Evapotranspiration Estimation ◽  
Missing Variables

ABSTRACT FAO Penman-Monteith (FO-PM) is considered the standard method for the estimation of reference evapotranspiration (ET0) but requires various meteorological data, which are often not available. The objective of this work was to evaluate the performance of the FAO-PM method with limited meteorological data and other methods as alternatives to estimate ET0 in Jaíba-MG. The study used daily meteorological data from 2007 to 2016 of the National Institute of Meteorology’s station. Daily ET0 values were randomized, and 70% of these were used to determine the calibration parameters of the ET0 for the equations of each method under study. The remaining data were used to test the calibration against the standard method. Performance evaluation was based on Willmott’s index of agreement, confidence coefficient and root-mean-square error. When one meteorological variable was missing, either solar radiation, relative air humidity or wind speed, or in the simultaneous absence of wind speed and relative air humidity, the FAO-PM method showed the best performances and, therefore, was recommended for Jaíba. The FAO-PM method with two missing variables, one of them being solar radiation, showed intermediate performance. Methods that used only air temperature data are not recommended for the region.

scholarly journals MÉTODOS DE ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA (ET0) NO MUNICÍPIO DE SANTA TERESA, ES

Irriga ◽  
2017 ◽  
Vol 22 (4) ◽  
pp. 701-714
Author(s):  
Andre Dalla Bernardina Garcia ◽  
José Carlos Mendonça ◽  
Claudio De Almeida Martins
Keyword(s):  
Water Resources ◽  
Solar Radiation ◽  
Reference Evapotranspiration ◽  
Irrigation Management ◽  
Absolute Error ◽  
Estimation Methods ◽  
Coefficient Of Determination ◽  
Espírito Santo ◽  
Espirito Santo ◽  
E Mail

MÉTODOS DE ESTIMATIVA DA EVAPOTRANSPIRAÇÃO DE REFERÊNCIA (ET0) NO MUNICÍPIO DE SANTA TERESA, ES  ANDRE DALLA BERNARDINA GARCIA1; JOSÉ CARLOS MENDONÇA2 E CLAUDIO MARTINS DE ALMEIDA3 1Instituto Federal do Espírito Santo, Rodovia ES 080, Km 93, São João de Petrópolis, CEP 29660-000, Santa Teresa, ES, Fone:(27)3259-7878, E-mail:[email protected]ório de Engenharia Agrícola/UENF, Av. Alberto Lamego, 2000,P1,sl 209, Horto, Campos dos Goytacazes, RJ, Fone (22) 2739-7308, E-mail: [email protected]ório de Engenharia Agrícola/UENF, Av. Alberto Lamego, 2000,P1,sl 209, Horto, Campos dos Goytacazes, RJ, Fone (22) 2739-7308, E-mail: [email protected]                                                                   1 RESUMO                                                                            Devido aos constantes debates ocorridos sobre a racionalização dos recursos hídricos, a busca de maneiras e boas práticas de utilização da água têm sido cada vez mais difundidas, principalmente na agricultura. Dentre os meios de preservar os recursos hídricos está o manejo de irrigação, por isso é muito importante realizar a estimativa da evapotranspiração de referência (ET0). Neste contexto, o presente trabalho foi desenvolvido para o município de Santa Teresa, localizado na meso região Central Espírito-Santense com o objetivo de avaliar e comparar diferentes métodos de estimativa da ET0 com o método de Penman-Monteith FAO56, considerado como padrão de calibração, na ausência de dados lisimétricos. Os métodos utilizados foram os de Hargreaves-Samani, Radiação Solar, Makkink, Jesen-Haise, Linacre e Penman Simplificado. O coeficiente de determinação (R2), índice de concordância de Willmott (D), o erro médio absoluto (MAE), o erro máximo (EMAX), a eficiência do método (EF) e o índice de desempenho (c) foram utilizados para avaliar os indicadores observados. Dentre os métodos avaliados, os que apresentaram melhores resultados foram os de Makkink e Penman Simplificado (R2 = 0,96 e 0,96; D= 0,99 e 0,97; MAE = 0,23 e 0,44; EMAX = 1,36 e 1,07; EF = 0,95 e 0,87 e c = 0,97 e 0,95) respectivamente, seguidos do método de Hargreaves-Samani (R2 = 0,86; D= 0,91; MAE = 0,60; EMAX = 2,16; EF = 0,69 e c = 0,85). Os resultados obtidos com os métodos de Linacre, Radiação Solar e Jensen-Haise foram inferiores e sendo a sua utilização não recomendada para a região de Santa Teresa, ES. Palavras-chave: Agrometeorologia, demanda hídrica, irrigação, Penman-Monteith  GARCIA, A. D. B.; MENDONÇA, J. C.; MARTINS, C. A.METHODS FOR ESTIMATING REFERENCE EVAPOTRANSPIRATION (ET0) FOR THE CITY OF SANTA TERESA, ES  2 ABSTRACT Due to constant discussion about rationalization of water resources, the search for ways and good practices in water use have been increasingly widespread, especially in agriculture. Among the means of preserving water resources is irrigation management, so it is very important to estimate the reference evapotranspiration (ET0). In this context, the present work was developed for the municipality of Santa Teresa, located in Central Espírito-Santo mesoregion with the objective of evaluating and comparing different ET0 estimation methods with Penman-Monteith FAO56 method considered as calibration standard, in the absence of lysimetric data. The methods used were those of Hargreaves-Samani, Solar Radiation, Makkink, Jesen-Haise, Linacre and Penman Simplified. The coefficient of determination (R2), Willmott concordance index (D), mean absolute error (MAE), maximum error (EMAX), method efficiency (EF) and performance index (c) were used for assessing the observed indicators. Among the evaluated methods, the ones with the best results were Makkink and Penman Simplified (R² = 0.96 and 0.96 D = 0.99 and 0.97, MAE = 0.23 and 0.44, EMAX = 1.36 and 1.07, EF = .95 and 0.87 and c = 0.97 and 0.95) respectively, followed by Hargreaves-Samani methods (R² = 0.86, D = 0.91, MAE = 0.60, EMAX = 2.16, EF = 0.69 and c = 0.85). The results obtained with the methods of Linacre, Solar Radiation and Jensen-Haise were lower and their use is not recommended for the region of Santa Teresa, ES. Keywords:  Agrometeorology, hydric demand, irrigation, Penman-Montheith 

scholarly journals Statistical Analysis for Prognosis of a Photochemical Smog Episode

2013 ◽  
Vol 9 (2) ◽  
pp. 20-24
Author(s):  
Camelia Gavrilă ◽  
Florinela Ardelean ◽  
Adriana Coman ◽  
Elena Burchiu
Keyword(s):  
Statistical Analysis ◽  
Solar Radiation ◽  
Prognostic Value ◽  
Meteorological Parameters ◽  
Real Data ◽  
Global Solar Radiation ◽  
Photochemical Smog ◽  
Climatic Parameters ◽  
Essential Information ◽  
Pollutant Concentrations

Abstract In this paper we describe the evaluation of various climatic parameters in establishing their prognostic value in a photochemical smog episode. Our application was validated using real data from the “Cercul Militar National” and “Sos. Mihai Bravu nr. 47-49”, from April 2008 to May 2008. The study was performed on hour averages of pollutant concentrations and meteorological parameters and the statistical analysis was based on multiple regressions. We concluded by using mathematical and statistical methods, [1], that an accurate Global Solar Radiation is one of the most important and essential information in the pollution report.

scholarly journals Evapotranspiração da cultura da cebola

2015 ◽  
Vol 10 (4) ◽  
pp. 58
Author(s):  
G. M. Oliveira ◽  
M. W. Silva ◽  
M. N. Daamen ◽  
E. C. S. Cavalcante ◽  
M. M. V. B. R. Leitão
Keyword(s):  
Social Sciences ◽  
Reference Evapotranspiration ◽  
Irrigation System ◽  
The State ◽  
Estimation Methods ◽  
Crop Evapotranspiration ◽  
Experimental Field ◽  
Evapotranspiration Estimation ◽  
Made In

<p><span>A determinação da quantidade de água necessária para as culturas é um dos principais fatores para o correto planejamento, dimensionamento e manejo de qualquer sistema de irrigação. O presente trabalho teve como objetivo, comparar medida da evapotranspiração da cultura (ETc) da cebola com estimativa obtida a partir da evapotranspiração de referência (ETo) determinada por diferentes métodos e Kc proposto na literatura. O experimento foi conduzido no campo experimental do Departamento de Tecnologia e Ciências Sociais da Universidade do Estado da Bahia - UNEB, em Juazeiro, no período de junho a setembro de 2011. As medidas da ETc foram obtidas em evapotranspirômetros e as estimativas, a partir de ETo determinada pelos métodos: Penman-Monteith (padrão FAO), Penman-Monteith modificado por Villa Nova et al. (2004), Hargreaves &amp; Samani, Makkink e Jensen &amp; Haise e Kc proposto por Marouelli et al. (2005), para a cultura da cebola.<strong> </strong>É fundamental a avaliação de métodos de estimativa da evapotranspiração de referência antes de sua aplicação, pois erros consideráveis podem ser cometidos na determinação da quantidade de água a ser aplicada a uma cultura, o que repercutirá certamente, na produtividade.</span></p><p align="center"><strong><em>Evapotranspiration crop onion</em></strong></p><p><strong>Abstract</strong><strong>: </strong>The determination of the amount of water needed for crops is a major factor for the correct planning, sizing and management of any irrigation system. This study aimed to compare measure of crop evapotranspiration (ETc) onion with estimates obtained from the reference evapotranspiration (ETo) determined by different methods and Kc proposed in the literature. The experiment was conducted in the experimental field of the Department of Technology and Social Sciences, University of the State of Bahia, in Juazeiro, from June to September 2011. The ETc measurements were obtained in evapotranspirometers and estimates, from ETo determined by the methods: Penman-Monteith (FAO standard), Penman-Monteith modified by Villa Nova et al. (2004), Hargreaves &amp; Samani, Makkink and Jensen &amp; Haise and Kc proposed by Marouelli et al. (2005), for the cultivation of onion. It is critical to evaluation of reference evapotranspiration estimation methods before their application because considerable mistakes can be made in determining the amount of water to be applied to a culture, which resonate certainly in productivity.</p><p><span><br /></span></p>

Using the ERA5 dataset of atmospheric variables to estimate daily reference evapotranspiration in Sicily, Italy.

2021 ◽  
Author(s):  
Giuseppe Provenzano ◽  
Matteo Ippolito
Keyword(s):  
Wind Speed ◽  
Solar Radiation ◽  
Air Temperature ◽  
Management Practices ◽  
Reference Evapotranspiration ◽  
Dew Point ◽  
Climate Data ◽  
Crop Evapotranspiration ◽  
Time Step ◽  
Mediterranean Countries

&lt;p&gt;Crop evapotranspiration (ET) plays a key role in many hydrological processes involving the soil-plant-atmosphere system. The concept of reference crop evapotranspiration (ET&lt;sub&gt;0&lt;/sub&gt;) was introduced to estimate the atmosphere evaporation demand independently of crop type, development stage and management practices. Among the available methods to estimate ET&lt;sub&gt;0&lt;/sub&gt;, the Penman-Monteith equation proposed by the Food and Agriculture Organization of the United Nations (FAO56-PM), is considered one of the most accurate, so that it is assumed as a reference to calibrate other simplified procedures. In several regions of the world, the limited availability of meteorological observations to estimate ET&lt;sub&gt;0&lt;/sub&gt; can be overcome by using gridded reanalysis dataset created by data assimilation of weather observations. Different datasets with relatively high spatial resolution but different in terms of Spatio-temporal resolution have been generated and are freely downloadable at the global scale. The latest ERA5-Land product released in 2019 is characterized by a spatial grid to 0.1&amp;#176; latitude and 0.1&amp;#176; longitude. The database provides several land variables at hourly time-step including, among others, air temperature, dew point temperature and solar radiation at 2.0 m above the soil surface, as well as the wind speed components at 10 m height.&lt;/p&gt;&lt;p&gt;The objective of the research was to assess the suitability of ERA5-Land dataset of climate data to predict daily reference evapotranspiration in Sicily, Italy. For the period 2006-2015, the performance of the reanalysis data to capture the local climate variables was assessed based on the comparison with the corresponding ground data measured by a network of 39 climate stations in Sicily belonging to the Agrometeorological Information Service (SIAS). After evaluating the statistical errors associated with each climatic variables retrieved from the ERA5-Land, the comparison between daily ET&lt;sub&gt;0&lt;/sub&gt; values obtained with the FAO56-PM and considering both the dataset was carried out.&lt;/p&gt;&lt;p&gt;The analysis showed that air temperature, solar radiation and wind speed retrieved by the ERA-5 dataset resulted in quite good agreement with the corresponding measured on the ground, with an average root mean square error (RMSE) equal respectively to 1.8&amp;#176;C, 2.9 MJm&lt;sup&gt;-2&lt;/sup&gt;d&lt;sup&gt;-1&lt;/sup&gt;, and 1.3 ms&lt;sup&gt;-1&lt;/sup&gt; and corresponding mean bias errors (MBE) of -0.4&amp;#176;C, 1.0 MJm&lt;sup&gt;-2&lt;/sup&gt;d&lt;sup&gt;-1&lt;/sup&gt;&amp;#160; and -0.1 ms&lt;sup&gt;-1&lt;/sup&gt;. On the other hand, relative air humidity was characterized by average values of RMSE and MBE respectively equal to 10.3% and 5.6%. When considering all the examined climate stations, the RMSE and MBE values associated with ET&lt;sub&gt;0&lt;/sub&gt; ranged from 0.4 to 1.3 mm d&lt;sup&gt;-1&lt;/sup&gt;, and -1.0 and 0.0 mm d&lt;sup&gt;-1&lt;/sup&gt;, supporting the possibility to consider the ERA-5 data to obtain suitable estimations of crop reference evapotranspiration even for other Mediterranean countries where measured climate data are not available.&lt;/p&gt;

scholarly journals Estimation methods of reference evapotranspiration (ETo) for Uberlândia -MG

2015 ◽  
Vol 35 (1) ◽  
pp. 27-38 ◽  
Author(s):  
ZILDA C. DE LACERDA ◽  
JOSÉ E. P. TURCO
Keyword(s):  
Solar Radiation ◽  
Reference Evapotranspiration ◽  
Global Solar Radiation ◽  
Daily Basis ◽  
Meteorological Station ◽  
Estimation Methods ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
Daily Data ◽  
Analysis Of Results

One approach to verify the adequacy of estimation methods of reference evapotranspiration is the comparison with the Penman-Monteith method, recommended by the United Nations of Food and Agriculture Organization - FAO, as the standard method for estimating ET0. This study aimed to compare methods for estimating ET0, Makkink (MK), Hargreaves (HG) and Solar Radiation (RS), with Penman-Monteith (PM). For this purpose, we used daily data of global solar radiation, air temperature, relative humidity and wind speed for the year 2010, obtained through the automatic meteorological station, with latitude 18° 91' 66" S, longitude 48° 25' 05" W and altitude of 869m, at the National Institute of Meteorology situated in the Campus of Federal University of Uberlandia - MG, Brazil. Analysis of results for the period were carried out in daily basis, using regression analysis and considering the linear model y = ax, where the dependent variable was the method of Penman-Monteith and the independent, the estimation of ET0 by evaluated methods. Methodology was used to check the influence of standard deviation of daily ET0 in comparison of methods. The evaluation indicated that methods of Solar Radiation and Penman-Monteith cannot be compared, yet the method of Hargreaves indicates the most efficient adjustment to estimate ETo.

scholarly journals Comparative Study of Evapotranspiration Variation and its Relationship with other Climatic Parameters in Asaba and Uyo

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Okwunna M Umego ◽  
Temitayo A Ewemoje ◽  
Oluwaseun A Ilesanmi
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Solar Radiation ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Small Variation ◽  
Climatic Variables ◽  
Maximum Temperature ◽  
Climatic Parameters ◽  
Sunshine Hours

This study was carried out to assess the variations of Reference Evapotranspiration (ETO also denoted with RET) calculated using FAO-56 Penman Monteith model of two locations Asaba and Uyo and evaluate its relationships with the variations of other climatic parameters. Meteorological data of forty one years (1975-2015) and thirty five years (1981-2015) period for Asaba and Uyo, respectively gotten from Nigeria Meteorological Agency, Abuja were used. It was observed that the variations of Evapotranspiration (ET) in both locations were in line with two seasons (rainy and dry) normally experienced in Nigeria having its highest value in March (4.8 mm/day) for Asaba and for Uyo in February (4.5 mm/day); and its lowest value in August (3.1 mm/day) for Asaba and in July (2.9 mm/day) for Uyo. ET variation when compared with other climatic variables in both locations was observed to have the same trend with maximum temperature, solar radiation and sunshine hours. It also has the same variation with minimum temperature though with slight deviation. It was observed that ET variation is inversely proportional to the variation relative humidity. Wind speed displayed relatively small variation in its trend over the study period and is not in line with the variations of ET.Keywords— Evapotranspiration, Climatic Variables, FAO Penman-Monteith Model, Variations

scholarly journals Performance evaluation of solar radiation equations for estimating reference evapotranspiration (ETo) in a humid tropical environment

2019 ◽  
Vol 42 (1) ◽  
pp. 124-135
Author(s):  
Emeka Ndulue ◽  
Ikenna Onyekwelu ◽  
Kingsley Nnaemeka Ogbu ◽  
Vintus Ogwo
Keyword(s):  
Solar Radiation ◽  
Reference Evapotranspiration ◽  
Meteorological Data ◽  
Accurate Estimate ◽  
Tropical Environment ◽  
Crop Evapotranspiration ◽  
Reference Crop Evapotranspiration ◽  
Field Crops ◽  
Essential Input ◽  
Reference Crop

Abstract Solar radiation (Rs) is an essential input for estimating reference crop evapotranspiration, ETo. An accurate estimate of ETo is the first step involved in determining water demand of field crops. The objective of this study was to assess the accuracy of fifteen empirical solar radiations (Rs) models and determine its effects on ETo estimates for three sites in humid tropical environment (Abakaliki, Nsukka, and Awka). Meteorological data from the archives of NASA (from 1983 to 2005) was used to derive empirical constants (calibration) for the different models at each location while data from 2006 to 2015 was used for validation. The results showed an overall improvement when comparing measured Rs with Rs determined using original constants and Rs using the new constants. After calibration, the Swartman–Ogunlade (R2 = 0.97) and Chen 2 models (RMSE = 0.665 MJ∙m−2∙day−1) performed best while Chen 1 (R2 = 0.66) and Bristow–Campbell models (RMSE = 1.58 MJ∙m−2∙day−1) performed least in estimating Rs in Abakaliki. At the Nsukka station, Swartman–Ogunlade (R2 = 0.96) and Adeala models (RMSE = 0.785 MJ∙m−2∙day−1) performed best while Hargreaves–Samani (R2 = 0.64) and Chen 1 models (RMSE = 1.96 MJ∙m−2∙day−1) performed least in estimating Rs. Chen 2 (R2 = 0.98) and Swartman–Ogunlade models (RMSE = 0.43 MJ∙m−2∙day−1) performed best while Hargreaves–Samani (R2 = 0.68) and Chen 1 models (RMSE = 1.64 MJ∙m−2∙day−1) performed least in estimating Rs in Awka. For estimating ETo, Adeala (R2 =0.98) and Swartman–Ogunlade models (RMSE = 0.064 MJ∙m−2∙day−1) performed best at the Awka station and Swartman–Ogunlade (R2 = 0.98) and Chen 2 models (RMSE = 0.43 MJ∙m−2∙day−1) performed best at Abakaliki while Angstrom–Prescott–Page (R2 = 0.96) and El-Sebaii models (RMSE = 0.0908 mm∙day−1) performed best at the Nsukka station.

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