Solar Ultraviolet Irradiance Characterization under All Sky Conditions in Burgos, Spain

Abstract

Solar Ultraviolet Radiation (UVR), which is identified as a major environmental health hazard, is responsible for a variety of photochemical reactions with direct effects on urban and aquatic ecosystems, human health, plant growth, and the deterioration of industrial systems. Ground measurements of total solar UVR are scarce, with low spatial and temporal coverage around the world, which is mainly due to measurement equipment maintenance costs and the complexities of equipment calibration routines; however, models designed to estimate ultraviolet rays from global radiation measurements are frequently used alternatives. In an experimental campaign in Burgos, Spain, between September 2020 and June 2022, average values of the ratio between horizontal global ultraviolet irradiance (GHUV) and global horizontal irradiance (GHI) were determined, based on measurements at ten-minute intervals. Sky cloudiness was the most influential factor in the ratio, more so than any daily, monthly, or seasonal pattern. Both the CIE standard sky classification and the clearness index were used to characterize the cloudiness conditions of homogeneous skies. Overcast sky types presented the highest values of the ratio, whereas the clear sky categories presented the lowest and most dispersed values, regardless of the criteria used for sky classification. The main conclusion, for practical purposes, was that the ratio between GHUV and GHI can be used to model GHUV.

Modeling Horizontal Ultraviolet Irradiance for All Sky Conditions by Using Artificial Neural Networks and Regression Models

“…The trigger frequency of the camera was 1 s and its image resolution was 1158 × 1172 pixels, recorded with the RGB color model (8-bit pixels with integer values between 0 and 255 were used). A complete description of the experimental facility and instruments can be found in previous works [14,38,39].…”

“…In many works, the ratio between the ultraviolet component and the horizontal global irradiance, (I I ⁄ ), has been studied, obtaining values of between 2.5% and 6% [13]. A complete review of this relation can be found in [14]. The ratio between both magnitudes is location dependent and is influenced by the clearness index, k ; when cloudiness increases, the ratio of I to I increases [15], i.e., the presence of clouds reduces the global horizontal irradiance to a greater extent than the UV component [16][17][18].…”

Modelización matemática de la radiación solar ultravioleta

“…En el tercer artículo de esta tesis [87], se ha aplicado el mismo procedimiento para modelar utilizando modelos de regresiones multilineales y de redes neuronales artificiales. La campaña experimental para la obtención de los datos es la misma que la utilizada en el segundo de los artículos de la tesis, entre septiembre de 2020 y junio de 2022.…”

“…Gráfico de cajas y bigotes de los promedios estacionales de basados en los conjuntos de 10 min (Fuente: [61]) .......... 30 Figura 11. Gráfico de cajas y bigotes del ratio basado en datos de 10 minutos agrupados por horas (Fuente: [87]) ........... 33…”

“…Figura 12. Gráfico de cajas y bigotes del ratio basado en datos de 10 minutos agrupados por meses (Fuente: [87]) .................. 34…”