# Solar Ultraviolet Irradiance Characterization under All Sky Conditions in Burgos, Spain
## 2 Experimental Data  
All meteorological and radiometric experimental data used in this study were recorded at the weather station of the SWIFT Research Group, located on the roof of the Higher Polytechnic School building (EPS) of Burgos University (42\({}^{\circ}\)21\({}^{\prime}\)04\({}^{\prime\prime}\) N, 3\({}^{\circ}\)41\({}^{\prime}\)20\({}^{\prime\prime}\) W, 856 m above mean sea level). Figure 1 shows the location of the meteorological station on the flat roof of the EPS building, which is where the climatic parameters were measured. These parameters were as follows: ambient temperature, relative humidity, atmospheric pressure, wind speed and direction, and rainfall. A Kipp & Zonen CUV5 sensor was used to measure _GHUV_. _GHI_ data were measured with a (Hulseflux, model SR11) pyranometer. Sky luminance and radiance distributions were determined with a commercial MS-321 LR sky scanner manufactured by EKO Instruments (EKO Instruments Europe B.V. Den Haag, The Netherlands). The technical specifications of the various measurement instruments are shown in Tables 2-4. A complete description of the experimental facility and its location can be found in previous papers [62;  
The experimental campaign ran from 14 September 2020 to 6 June 2022. _GHI_ and _GHUV_ data were recorded every 10 min (average recorded scans of 30 s). Experimental _GHI_ data were subjected to the Quality Control (QC) procedure proposed for the MESoR project [64]. Regarding UV data, it was established that \(GHUV\) could not be higher than the extraterrestrial UV on the horizontal plane (\(UVH_{0}\)) that corresponded with the same time frame. \(UVH_{0}\) was calculated with the correction factor (\(f_{c}\)) applied to the UV solar constant (\(UV_{sc}\)); this is based on the estimated orbital eccentricity multiplied by the cosine of the solar zenith angle, as shown in Equation (1). \[UVH_{0}=f_{c}UV_{sc}\cos\theta_{z}. \tag{1}\]  
In the absence of a standardized value, the \(UV_{sc}\) was obtained from the integration of the solar spectrum, as revised by [PERSON] [65], between 280 and 400 nm, subsequently obtaining a value of 102.15 W\(\cdot\)m\({}^{-2}\). Data corresponding to solar elevation angles lower than 5\({}^{\circ}\) were discarded, in order to avoid the cosine response problems of the _GHI_ and _GHUV_ measurement instruments. The sky scanner was adjusted monthly so that it could take measurements from sunrise to sunset. It completed a full scan in four minutes and started a new scan every ten minutes. Data that were not within the specifications (i.e., \(\alpha_{s}\leq 7.5^{\circ}\), \(>50\) kcd\(\cdot\)m\({}^{-2}\) and \(<0.1\) kcd\(\cdot\)m\({}^{-2}\)) were discarded. If a dataset (_GHI_, _GHUV_, or sky scanner measurement) failed to pass the QC, then all the simultaneous datasets were rejected; thus, 24.9% of the data recorded during the 22 month experimental campaign were rejected after failing the quality control tests, resulting in 34,270 valid 10 min data points. The seasonal data distribution was 22.8% in winter, 30.5% in spring, 20.3% in summer, and 26.3% in autumn. Table 5 shows the annual and seasonal mean values of _GHI_, _GHUV_, temperature (\(T\)), relative humidity (\(RH\)), and wind speed (\(WS\)), which were calculated from the 10 min records. These values were obtained for the whole year and they were classified according to each sky type, \(k_{t}\) (overcast \(0\leq k_{t}\leq 0.35\), partly cloudy \(0.35<k_{t}\leq 0.65\), clear sky \(0.65<k_{t}\leq 1\)) [66]. \begin{table}
\begin{tabular}{l l} \hline \hline
**Model** & **MS-321 LR Sky Scanner** \\ \hline FOV & 11\({}^{\circ}\) \\ Luminance & 0 to 50 kcd/m\({}^{2}\) \\ Radiance & 0 to 300 W/m\({}^{2}\) \\ A/D Convertor & 16 bits \\ Calibration Error & 2\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Sky scanner technical specifications.