# Extension of PAR Models under Local All-Sky Conditions to Different Climatic Zones
## 2 Description of the Experimental Data  
Figure 1 shows the location of the weather station in Burgos, Spain (42\({}^{\circ}\)21\({}^{\prime}\)04\({}^{\prime\prime}\) N, 3\({}^{\circ}\)41\({}^{\prime}\)20\({}^{\prime\prime}\) W, 856 metres Above Mean Sea Level) (AMSL) where the data were collected for this study. The prevailing climate in Burgos, both oceanic and Mediterranean, is classified as Csb in the Koppen climate classification system This weather station, described in previous work [25], is situated on the flat roof of a building at the University of Burgos, with no external obstructions or reflections from other surfaces. In addition, data were collected from all seven stations within the Surface Radiation Budget Network (SUFRAD), dependent on the National Oceanic and Atmospheric Administration (NOAA): Bondville station, Sioux Falls station, Boulder station, Desert Rock station, Fort Peck station, Goodwin Creek Station, and Penn State station. Figure 2 shows the location of the weather station in Burgos and the location of the seven SURFRAD weather stations.  
In Burgos, _RaGH_ and Diffuse Horizontal Irradiation (_RaDH_) were measured in W\(\cdot\)m\({}^{-2}\) using a Hukseflux pyranometer, model SR11, and a Hukseflux pyheliometer, model DR01, respectively. _PAR_ was measured from Photosynthetic Photon Flux Density, \(Q_{p}\) (\(\upmu\)mol\(\cdot\)s\({}^{-1}\cdot\)m\({}^{-2}\)), data and was then converted into _PAR_ data (W\(\cdot\)m\({}^{-2}\)) using [PERSON]'s conversion factor (4.57 \(\upmu\)mol\(\cdot\)J\({}^{-1}\)) [26] using a EKO quantum sensor, model ML-020P. All meteorological and radiometric data were recorded every ten minutes (averages from 30 s). The experimental campaign took place from April 2019 to February 2021. Experimental data were analyzed and then filtered using conventional quality criteria [27]. If a dataset failed to pass the quality criteria, then all simultaneous datasets were rejected. The original dataset counted 71,600 datums (ten-minute datasets), 36% of which were eliminated after the filtering procedure. In the USA, _PAR_, global, and diffuse irradiance values are given in W\(\cdot\)m\({}^{-2}\). The _PAR_ values were measured employing a LI-COR Quantum sensor, while the _RaGH_ values were measured using a pyranometer Spectrolab SR-75, and _RaDH_ was measured with an Eppley, Model 8-48 pyroanometer. The experimental campaign spanned 10 years, from January 2009 to December 2018 at each station, with a temporal resolution of 1 min, moving to ten-minute values by calculating the average of the values within that interval.  
Burgos University, Spain. The \(Q_{p}\), \(RaGH\), and \(RaDH\) sensors are shown in the detailed pictures.  
Each Meteorological Index (MI) shown in Table 1 was determined at the single Spanish station and the seven meteorological stations in the USA. The following meteorological indices were directly obtained from the experimental measurements: \(T\), \(P\), \(RaGH\), and \(PAR\), obtained from \(Q_{p}\), which were measured with pyranometers and a quantum sensor, respectively. The solar azimuth cosine (\(cosZ\)) was calculated from the geometrical data of the location, using well-established mathematical relationships [28]. Finally, the dew point temperature (\(T_{d}\)) was calculated from the vapour water pressure [29] and \(RH\). The other indices, \(k_{t}\)[28], the horizontal diffuse fraction, \(k_{d}\)[30], and [PERSON]'s clearness index, \(\varepsilon\), and [PERSON]'s brightness factor, \(\Delta\)[31], were calculated using equations described elsewhere [32].  
Figure 1: Experimental facility on the roof of the Higher Polytechnic School of.  
Figure 2: Location of the weather stations (Burgos and USA).