## 4 Results and Discussion
### Results of the Daily Online Analysis (Horizontal Polarization)  
Figure 2 shows the daily analysis of the Sun's signals detected during the operational scan program by the new generation MeteoSwiss meteorological radars operating at the C-band. As in Figure 1, the results are shown from 1 January until 12 August 2014 (Julian Day 224); the retrieved solar flux values in sfu are also transformed to decibels. The solar \"monthly\" oscillation is clearly visible in all of the radar systems and shows good correlation (see the first line of Table 2) to the reference (DRAO at 20 UTC, as described in the previous section): the Albis radar shows the best agreement with the highest  
\begin{table}
\begin{tabular}{c c c c} \hline  & **DRAO 20 UTC** & **DRAO 18 (17) UTC** & **DRAO 22 (23) UTC** \\ \hline DRAO 20 UTC & 0 dB & 0.041 dB & 0.044 dB \\ DRAO 18 (17) UTC & 0.040 dB & 0 dB & 0.056 dB \\ DRAO 22 (23) UTC & 0.044 dB & 0.057 dB & 0 dB \\ \hline \end{tabular}
\end{table}
Table 1: Agreement in terms of scatter (in dB) between the three 1-h long Sun measurements acquired by the DRAO in Canada.  
Figure 1: Daily solar flux values measured by the Dominion Radio Astrophysical Observatory (DRAO) in Canada at 10.7 cm and extrapolated to the C-band. Each flux determination takes an hour. Note that S\({}_{0}\) = 1 sfu = 10\({}^{-22}\) W\(\cdot\)m\({}^{-2}\cdot\)Hz\({}^{-1}\).  
correlation and lowest scatter. A random component (daily fluctuations) seems to affect the radar estimates: a three-day median average (smoothing) is able to make the radar curves more similar to the reference and improve the correlation (see Section 4.3).  
The same agreement and similar scores are obtained when the 22 (23) and 18 (17) UTC time series are used: our interpretation is that the two selected scores are robust and can be used effectively for a quantitative evaluation of the radar _versus_ reference (DRAO) agreement. When using the (less robust) standard deviation of the log-transformed ratios, the Albis radar again shows the best agreement (last line in Table 2). A possible explanation for the better results of the Albis radar could be the use of the stable, new generation calibration unit.  
Such values can be compared with those obtained for the Dutch De Bilt radar by [PERSON] _et al._[2] in 2005 using DRAO 22 UTC as a reference: the standard deviation is 0.44 dB for the whole year (excluding three days with flares) and is 0.58 dB and 0.44 dB for the first nine months of the year, with (272 days) and without (269 days) the above-mentioned three flares, respectively. As expected, the scatter values are much less sensitive to the three flares: such values are 0.27 dB (272 days) and 0.26 dB (269 days), respectively. Another interesting benchmark is the value shown by  
\begin{table}
\begin{tabular}{c c c c} \hline  & **Albis Radar** & **Lema Radar** & **Dole Radar** \\ \hline Explained variance in \% & 83\% & 74\% & 62\% \\ Scatter in dB & 0.28 dB & 0.42 dB & 0.44 dB \\ Standard deviation in dB & 0.35 dB & 0.48 dB & 0.48 dB \\ \hline \end{tabular}
\end{table}
Table 2: Agreement between the Swiss radar horizontal channel and the DRAO reference (20 UTC).  
Figure 2: Daily variability of the Sun’s emission retrieved from the MeteoSwiss weather radars in Lema, Dole and Albis. The values from DRAO (20 UTC) are plotted for reference purposes.  
[PERSON] _et al._[4] for the Finnish Anjalankoski radar over a period of two months at the end of 2011: the standard deviation is as small as 0.24 dB.  
Why is the amplitude of the oscillation of the DRAO reference signal smaller than those retrieved by radars? A possible explanation could be related to the transposition formula (Equation (1)) from the S-band to the C-band, which is less accurate when solar activity increases. For instance, applying a slope coefficient of 0.8 instead of 0.7155 in Equation (1) causes a reduction of both the scatter and standard deviation for all three Swiss radars.