Global solar radiation estimation from measurements of visibility and air temperature extremes

ABSTRACT

Solar radiation is the main source of energy for the survival of life and its associated activities. It is important to know accurate solar radiation value in areas such as agricultural activities, solar energy systems, heating, and meteorology. In this study, we present a model for the estimation of solar radiation value with other meteorological parameters in cases where solar radiation cannot be measured or not available. This model is based on the relationship between solar radiation and measured air temperature and visibility extremes. As is known, the incident global solar radiation is attenuated by clouds, aerosols, ozone layer, water vapor, etc.. In the model, the attenuation of the solar radiation is expressed by dew point temperature, visibility, and the maximum and minimum air temperatures. Dew-point temperature refers to the effect of water vapor on solar radiation, air temperature extremes are used to signify cloudiness. Visibility also gives the effect on the attenuation of solar radiation by air pollutants and aerosols in the model. The model was applied to the data taken from meteorological stations in Turkey. Error analysis was performed and compared with the models in the literature and satisfactory results were obtained.

Abbreviations H: Daily total global solar radiation, units of MJ • m⁻² • day⁻¹; H₀: Extraterrestrial solar radiation, units of MJ • m⁻² • day⁻¹; H_m: Measured daily total global solar radiation, units of MJ • m⁻² • day⁻¹; H_c: Calculated daily total global solar radiation, units of MJ • m⁻² • day⁻¹; T_min: Daily minimum temperature, units of °C; T_max: Daily maximum temperature, units of °C; RH: T_dew: Relative humidity, units of %rh; Dew-point temperature, units of °C

KEYWORDS:

• Solar radiation
• visibility
• daily total global solar radiation
• meteorological models
• model validation