Models to estimate incident solar radiation on Seropédica, Rio de Janeiro

Givanildo De Gois,Jessica Cristina Santos Souza,José Francisco De Oliveira-Júnior,Rafael Coll Delgado,Gustavo Bastos Lyra,Paulo Eduardo Teodoro

doi:10.14393/bj-v32n2a2016-29877

Abstract

Incident solar radiation (R s ) is usually used as an input variable in growth simulation models and yield of agricultural crops, in the design of alternative energy systems, buildings desing, weather, irrigation projects and food preservation, among others. However, in Brazil, there are few studies that evaluated the performance of different models in estimating R s . Therefore, the aim of the study is to evaluate the Hargreaves-Samani, Thornton-Running and Weiss models to estimate R s in the municipality of Seropedica, Rio de Janeiro. We used hourly measurements of solar radiation (R s , KJ m -2 ) and maximum (t x ,°C) and minimum (t n ,°C) air temperature obtained from Ecologia Agricola station (EA), between January/2008 to December/2013. Normality (Shapiro-Wilks and Jarque-Bera) and homogeneity of variance (Bartlett) tests were applied to the data set. The performance of the models was evaluated based on different statistical parameters (r 2 RMSE, d, ρ s and Student’s t-test). The results indicated the rejection of the variance normality hypothesis of the standardized residuals by Shapiro-Wilks and Jarque-Bera tests. Bartlett’s test indicated the presence of heterogeneity of model estimates. Hargreaves-Samani and Thornton-Running models obtained high values forr 2 and low values for d. Hargreaves-Samani (coastal) model excelled in relation to other, being more suitable for estimating the R s in the municipality of Seropedica, Rio de Janeiro.

Highlights

Solar radiation is the main source of energy for many physical, chemical and biological processes occurring in the Earth system, and provide energy for atmospheric movements and, determine weather and climate spatiotemporal patterns (CASTELLVÍ, 2008; JERSZURKI; SOUZA, 2013)
Hagreaves and Samani (1982) were the precursors in the estimation of incident solar radiation based on air temperature, according to Equation 1. These authors adopted two patterns for kt value for estimating the radiação solar incidente (Rs); one for the interior regions, where weather patterns are dominated by large air masses; another to coastal regions, where weather patterns are dominated by the proximity to the coastal environment. We evaluated both kt values because Seropédica is situated near a large body of water (Baía de Sepetiba, 18.5 km), following by Oceano Atlântico (25 km) and, receives influence of both bodies of water
The results obtained by Shapiro-Wilks (SW) and Jarque-Bera (JB) normality tests and Bartlett's variance homogeneit indicated the rejection of standardized residuals normality of variance hypothesis with p-value below level of significance at 5% probability in all models (Table 1)

Summary

Introduction

Solar radiation is the main source of energy for many physical, chemical and biological processes occurring in the Earth system, and provide energy for atmospheric movements and, determine weather and climate spatiotemporal patterns (CASTELLVÍ, 2008; JERSZURKI; SOUZA, 2013). It is directly responsible for air and soil heating (sensible heat flux), photosynthesis and evapotranspiration (latent heat flux), all direct impact on human activities (CARVALHO et al, 2011) and, currently, has been used as alternate energy source. It is indispensable understand its spatial and temporal variation (SILVA et al, 2012)

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