Comparison of Standardized Reference Evapotranspiration Equations in Southern Spain

Jiménez-Gavilán, Pablo; Estévez, Javier; Berengena, J.

doi:10.1061/(asce)0733-9437(2008)134:1(1)

Cited by 69 publications

(44 citation statements)

References 23 publications

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“…O fator de correção para ajuste dos dados funcionaria, na prática, como fator de calibração do piranômetro. Outros autores (Samani et al, 2007;Gavilan et al, 2008) têm adotado esse procedimento como critério de controle da qualidade de dados de R s em estudos de evapotranspiração.…”

Section: Radiação Solar Ajustadaunclassified

Avaliação de modelos de estimativa da radiação solar incidente em Cruz das Almas, Bahia

Borges¹,

Oliveira

Filho

et al. 2010

Rev. bras. eng. agríc. ambient.

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RESUMOEm estudos agroambientais a radiação solar incidente (R s ) é uma das mais importantes variáveis meteorológicas. Na ausência de dados observados de R s é possível estimá-los mediante modelos. O objetivo deste estudo foi avaliar modelos baseados na temperatura do ar para estimativa diária de R s nas condições do Recôncavo Sul da Bahia. Utilizaram-se dados de R s do período de 2004 a 2006, medidos por uma estação meteorológica automática pertencente ao INMET, instalada em Cruz das Almas, Bahia. Como etapa preliminar, verificou-se a qualidade dos dados de R s tomando-se como referência curvas de radiação esperada em dias claros. Os seguintes modelos foram avaliados: Hargreaves-Samani para regiões interiores e regiões costeiras, Thornton-Running e o de Weiss. O desempenho de cada método foi avaliado através dos seguintes indicadores: coeficiente de determinção (R 2 ), razão média (RM), erro absoluto médio (EAM), raiz quadrada do quadrado médio do erro (RQME) e índice de concordância de Wilmott Evaluating models for estimation of incoming solar radiation in Cruz das Almas, Bahia, Brazil ABSTRACT Solar radiation at the earth's surface (R s ) is one of the essential weather variables for several agro-environmental studies. In the absence of measured R s , it's possible to simulate them by models. Using three years of daily R s data (2004)(2005)(2006) collected by an INMET (Brazilian Meteorological Service) automatic weather station installed in the municipality of Cruz das Almas, BA, three air temperature-based R s simulation models were evaluated. As a preliminary step, data quality was investigated and, when needed, adjustments were made based on clear sky solar radiation envelopes. The following models were evaluated: Hargreaves-Samani for both interior and coastal regions, Thornton-Running, and the Weiss model. Linear regression R 2 , mean ratio (MR), mean absolute error (MAE), root mean square error (RMSE), and the index of agreement of Willmott (d W ) were used for model performance evaluation against measured R s . The results recommended the coastal-region Hargreaves-Samani for prediction of R s in the Reconcavo of Bahia, Brazil, since it presented the MR value closest to 1.00 (1.01), the lowest MAE (2.54 MJ m -2 d -1 ), the lowest RMSE (3.13 MJ m -2 d -1 ), and the highest d W (0.90).

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Section: Radiação Solar Ajustadaunclassified

Avaliação de modelos de estimativa da radiação solar incidente em Cruz das Almas, Bahia

Borges¹,

Oliveira

Filho

et al. 2010

Rev. bras. eng. agríc. ambient.

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“…As comparações entre os valores de ETPPM e ETPH, e de ISPM e ISH foram obtidas por meio dos coeficientes de determinação (R 2 ) e angulares dos modelos de regressão linear, sendo as retas forçadas a passar pela origem., , Também foi utilizado o índice c, proposto por Camargo e Sentelhas (1997) Gavilán et al (2008), a ETPH apresenta alta variabilidade espacial no sul da Espanha, sendo que a precisão da eq.2 é afetada pelas médias anuais da demanda evaporativa e da velocidade do vento.…”

Section: Methodsunclassified

Uso da temperatura para cálculo do índice de seca de regiões produtoras de uva

2012

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RESUMO-O Sistema de Classificação Climática Multicritérios Geovitícola (CCM), empregado na caracterização climática de regiões produtoras de uvas, é composto pelos índices Heliotérmico (IH), de Frio Noturno (IF) e de Seca (IS) sendo que este se baseia no balanço hídrico potencial do solo. Para se calcular os valores de IS, são necessários dados da precipitação pluvial e da evapotranspiração potencial (ETP), estimados pelo método-padrão de Penman-Monteith. Nem todas as regiões vitícolas, no entanto, apresentam as variáveis meteorológicas necessárias para o uso desse método. Daí a importância de métodos que permitem estimar a ETP com base apenas em dados da temperatura do ar, como o de Hargreaves. No presente trabalho, foram comparados os Índices de Seca calculados com base nos valores de ETP estimados, empregando-se os métodos de Penman-Monteith e Hargreaves, para diferentes regiões vitícolas do mundo. Foram utilizados dados climáticos de 83 estações meteorológicas, representativas de regiões vitícolas localizadas em 18 países. A equação de Hargreaves obteve um desempenho classificado como muito bom, podendo ser adotada no sistema CCM, quando não se dispõe de dados para o uso do método de Penman-Monteith. Termos para indexação: viticultura, videira, zoneamento climático. USING TEMPERATURE TO CALCULATE THE DRYNESS INDEX OF GRAPE PRODUCTION REGIONSABSTRACT -The Geoviticulture Multicriteria Climatic Classification System (CCM), used to characterize the climate in grape production regions, is composed by the Heliothermal Index (HI), the Cool Night Index (CI) and the Dryness Index (DI), which is based on the potential soil water balance. The calculation of DI values requires precipitation and evapotranspiration potential (ETP) data, estimated using the standard Penman-Monteith method. However, not all grape regions have the climatic variables required to use this ETP method. Therefore, it is important to use other methods to estimate ETP based only on air temperature available data, such as the Hargreaves ETP method. The present study compared the Drought Index values calculated using the Penman-Monteith and the Hargreaves methods for different grape growing regions of the world. Climate data from 83 meteorological stations were used, representing grapevine regions located in 18 countries. The Hargreaves equation achieved a very good performance and can be used in the CCM system in places where there are insufficient data for the Penman-Monteith method.

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“…This novel approach to derive R nl was compared to the R nl model of the FAO-56 approach (Allen et al, 1998), originally derived to obtain daily estimates of R nl (using minimum and maximum daily T a divided by 2 instead of T a in Eq. 7) but commonly applied at hourly timescales (ASCE-EWRI, 2005;Perera et al, 2015;Gavilán et al, 2008;López-Urrea et al, 2006):…”

Section: Net Radiation (R N )mentioning

confidence: 99%

“…Several studies showed that the FAO-56 R nl submodel underestimates the magnitude of R nl for reference grass vegetation and poorly describes the diurnal pattern (Matsui, 2010;Blonquist Jr. et al, 2010;Yin et al, 2008;Temesgen et al, 2007). As mentioned, the FAO-56 R nl submodel was originally developed for reference grass vegetation under well-watered conditions for daily time steps, but is commonly applied at hourly timescales (ASCE-EWRI, 2005;Perera et al, 2015;Gavilán et al, 2008;López-Urrea et al, 2006;Irmak et al, 2005). At daily time steps, T s is close to T a , since the warmer daytime T s is compensated by the cooler nighttime T s .…”

Section: Net Longwave Radiationmentioning

confidence: 99%

Quantifying energy and water fluxes in dry dune ecosystems of the Netherlands

Voortman

Bartholomeus

Zee

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. Coastal and inland dunes provide various ecosystem services that are related to groundwater, such as drinking water production and biodiversity. To manage groundwater in a sustainable manner, knowledge of actual evapotranspiration (ET a ) for the various land covers in dunes is essential. Aiming at improving the parameterization of dune vegetation in hydrometeorological models, this study explores the magnitude of energy and water fluxes in an inland dune ecosystem in the Netherlands. Hydrometeorological measurements were used to parameterize the Penman-Monteith evapotranspiration model for four different surfaces: bare sand, moss, grass and heather. We found that the net longwave radiation (R nl ) was the largest energy flux for most surfaces during daytime. However, modeling this flux by a calibrated FAO-56 R nl model for each surface and for hourly time steps was unsuccessful. Our R nl model, with a novel submodel using solar elevation angle and air temperature to describe the diurnal pattern in radiative surface temperature, improved R nl simulations considerably. Model simulations of evaporation from moss surfaces showed that the modulating effect of mosses on the water balance is species-dependent. We demonstrate that dense moss carpets (Campylopus introflexus) evaporate more (5 %, +14 mm) than bare sand (total of 258 mm in 2013), while more open-structured mosses (Hypnum cupressiforme) evaporate less (−30 %, −76 mm) than bare sand. Additionally, we found that a drought event in the summer of 2013 showed a pronounced delayed signal on lysimeter measurements of ET a for the grass and heather surfaces, respectively. Due to the desiccation of leaves after the drought event, and their feedback on the surface resistance, the potential evapotranspiration in the year 2013 dropped by 9 % (−37 mm) and 10 % (−61 mm) for the grass and heather surfaces, respectively, which subsequently led to lowered ET a of 8 % (−29 mm) and 7 % (−29 mm). These feedbacks are of importance for water resources, especially during a changing climate with an increasing number of drought days. Therefore, such feedbacks need to be integrated into a coupled plant physiological and hydrometeorological model to accurately simulate ET a . In addition, our study showed that groundwater recharge in dunes can be increased considerably by promoting moss vegetation, especially of open-structured moss species.

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Comparison of Standardized Reference Evapotranspiration Equations in Southern Spain

Cited by 69 publications

References 23 publications

Avaliação de modelos de estimativa da radiação solar incidente em Cruz das Almas, Bahia

Avaliação de modelos de estimativa da radiação solar incidente em Cruz das Almas, Bahia

Uso da temperatura para cálculo do índice de seca de regiões produtoras de uva

Quantifying energy and water fluxes in dry dune ecosystems of the Netherlands

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