## 3 Results
### Weissfulbugifel (WEI) Radar at an Altitude of 2850 m in Grisons (Next to Davos)  
The WEI radar is the fifth and most recent dual-polarization system installed in Switzerland. It is located next to Davos on the top of the _Weissfulbugifel_ (lat. : 46.2843\({}^{\circ}\); long. : 8.5120\({}^{\circ}\)) at an altitude of 2850 m. During the site acceptance tests of the WEI system in autumn 2015, we were able to perform seven sun-tracking observations during six days (from 14 to 22 October, close to a Sun relative minimum). Two additional ones were acquired on 22 February and 21 March 2016, also close to a relative minimum. Results are listed in Table 2. Taking the average in logarithmic units, the mean solar flux from DRAO measurements is 21.64 \(\pm\) 0.30 dBsfu. As expected, the dispersion associated with the radar-retrieved values is slightly larger, that is, \(\pm\)0.37 (0.32) dB for H (V). In absolute terms, the average value obtained by the radar H (V) channel is \(-\)0.07 (\(-\)0.24) dB smaller. The difference between the two channels corresponds to an average mutual bias between H and V equal to +0.17 \(\pm\) 0.10 dB. DRAO values are corrected for atmospheric attenuation, whereas \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{1}{c}{_Weissfulbugifel_} & \multicolumn{2}{c}{_Monte Lema_} & \multicolumn{2}{c}{**Albis**} & \multicolumn{2}{c}{_La Dole_} & \multicolumn{2}{c}{_P. de la Plaine Morte_} \\ \hline
**H** & **V** & **H** & **V** & **H** & **V** & **H** & **V** & **H** & **V** \\ \hline
2.5 dB & 2.7 dB & 2.6 dB & 2.15 dB & 2.25 dB & 2.4 dB & 2.7 dB & 2.8 dB & 2.25 dB & 2.55 dB \\
44.8 dB & 45.0 dB & 45.0 dB & 45.0 dB & 45.2 dB & 45.0 dB & 45.0 dB & 45.1 dB & 44.6 dB & 44.7 dB \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Overall receiver losses (1 st line) and antenna gain (last line) of the five MeteoSwiss radar receivers. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{1}{c}{\multirow{2}{*}{**Date**}} & \multicolumn{2}{c}{**DRAO**} & \multirow{2}{*}{**I\({}_{\textbf{5.5}}\) Rx H**} & \multirow{2}{*}{**I\({}_{\textbf{5.5}}\) Rx V**} & **10 log** & **10 log** & **10 log** \\  & & **Reference** & & & **(H/V)** & **(H/DRAO)** & **(V/DRAO)** \\ \hline
14 October 2015 & 21.40 \(\pm\) 0.067 & 21.15 & 20.96 & 0.19 dB & \(-\)0.25 dB & \(-\)0.44 dB \\
15 October 2015 & 21.51 \(\pm\) 0.074 & 21.50 & 21.26 & 0.24 dB & \(-\)0.01 dB & \(-\)0.25 dB \\
17 October 2015 & 21.71 \(\pm\) 0.084 & 21.85 & 21.51 & 0.34 dB & \(+\)0.14 dB & \(-\)0.20 dB \\
20 October 2015 & 21.92 \(\pm\) 0.009 & 21.75 & 21.66 & 0.09 dB & \(-\)0.17 dB & \(-\)0.26 dB \\
21 October 2015 & 21.95 \(\pm\) 0.060 & 21.90 & 21.76 & 0.14 dB & \(-\)0.05 dB & \(-\)0.19 dB \\
22 October 2015 & 21.90 \(\pm\) 0.075 & 21.95 & 21.71 & 0.24 dB & \(+\)0.05 dB & \(-\)0.19 dB \\
22 October 2015 & 21.90 \(\pm\) 0.075 & 21.85 & 21.61 & 0.24 dB & \(-\)0.05 dB & \(-\)0.29 dB \\
22 February 2016 & 21.30 \(\pm\) 0.024 & 21.25 & 21.21 & 0.04 dB & \(-\)0.05 dB & \(-\)0.09 dB \\
21 March 2016 & 21.16 \(\pm\) 0.017 & 20.95 & 20.91 & 0.04 dB & \(-\)0.21 dB & \(-\)0.25 dB \\ \hline Average & 21.64 & 21.57 & 21.40 & +0.17 & \(-\)0.07 & \(-\)0.24 \\ Standard dev. & \(\pm\)0.30 & \(\pm\)0.37 & \(\pm\)0.32 & \(\pm\)0.10 & \(\pm\)0.13 & \(\pm\)0.10 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Solar flux values from nine Sun-tracking observations at the 2850-m WEI site in Grisons and corresponding nearest-in-time reference values by the Dominion Radio Astrophysical Observatory. no correction is applied for the values retrieved from the radar. At an altitude of 3000 m, clear sky gaseous attenuation at zenith is in the order of 0.1 dB. This fact, once properly modeled and taken into account, will reduce the negative bias of both radar channels.