A Simple All Weather Model to Estimate Ultraviolet Solar Radiation (290–385 nm)

Abstract

A new expression to estimate the solar ultraviolet irradiance from parameters usually available in radiometric networks is presented. The authors have analyzed the relation between solar ultraviolet global irradiance (290?385 nm), UV, and broadband global irradiance, G, studying as well the ratio UV/G. The analysis of the dependence between the ultraviolet global irradiance and the broadband global irradiance, both normalized to their respective extraterrestrial values, has been used in order to develop a functional dependence between both global hemispherical transmittances. The cloud radiative effect on both radiometric fluxes has also been studied. After this analysis, the authors propose a new expression to obtain ultraviolet global irradiance from only two input variables: clear-sky ultraviolet irradiance and the global broadband hemispherical transmittance. The dataset used in this paper has been registered in two-radiometric stations: one located in the outskirts of Granada (37.18°N, 3.58°W, 660 m above mean sea level), an inland location in southeastern Spain, during a 2-yr period, and the second located at Almería (36.83°N, 2.41°W), a coastal location, during a 3-yr period. Data from this last station have been used to validate the expressions obtained with the data from Granada. The results with this new model are satisfactory, with a mean bias error of 0.3% and a root-mean-square error of 2.3%.