## 3 Results and Discussion
### Station Performance at the Foret Montmoreny NEIGE Site near Quebec  
The SnowSense station was installed in October 2017 at the NEIGE site at Foret Montmoreny and was operational during the entire snow-covered winter season 2017/18. The power supply and the communication unit resisted the cold and windy environment without damage or failure. The station delivered continuous daily SWE and LWC measurements without any significant discontinuities (Figure 5a). In general, the SWE values derived by the SnowSense GNSS in situ station are in good agreement with the provided reference measurements by the two GMON CS725 sensors and the manual snow pit measurements (Figure 5b). The GMON sensor as well as the GNSS sensor are both non-destructive measurement methods and are largely capable of deriving SWE. Both sensors were already validated against other sensors like snow pillows and manual measurements (e.g., [7; 11; 44]). As stated by [PERSON] et al. [6], at the observed study site NEIGE, an average error of 18% between manual measurements and the GMON sensor is reasonable, and, for SWE levels less than 400 mm w.e., the estimation is inside the 5-10% range. At the time the GNSS measurements started in early winter 2017, the GNSS-derived SWE as well as the measurements of the two GMON sensors lay in a similar range at approximately 100 mm w.e. At the end of April 2018, the maximum amount of SWE with approximately 500 mm w.e. was reached, which was indicated by the GNSS solution as well as the manual measurements and one GMON sensor. Comparing the two GMON sensors (blue solid and blue dashed line, Figure 5b), however, an offset of the SWE measurement of up to 30% occurred between them. This offset was low in the beginning of the time series and increased during the winter continuously. The reasons for this might originate in different sensor locations e.g., with slightly different wind conditions, and are still under discussion, but are out of the scope of this paper. The manual measurements were performed 16 times on a weekly basis during the snow season. On each day, three to four snow pits were analyzed. The resulting averaged SWE measurements from the snow pits lie well in between the range of the two GMON sensors. The SWE results of the SnowSense GNSS station (black solid line) follows in the beginning of the season the lower GMON sensor (CS725_TL, blue dashed line). Since 20 February, after a heavy precipitation event, the GNSS derived SWE jumps to the level of the GMON sensor with the higher SWE values (CS725_K, blue solid line). The coefficient of determination (\(\mathbf{R^{2}}\)) between the GNSS data and the data from the GMON sensors is 0.53 for CS725_TL and 0.93 for CS725_K, respectively. Throughout the entire season, the GNSS measurements agree very well with the manual measurements from snow pits including their minimum and maximum values. Here, the coefficient of determination (\(\mathbf{R^{2}}\)) is 0.64. For all \(\mathbf{R^{2}}\) and root mean square errors (RMSE) errors of the validation study, we refer to Table 1. \begin{table}
\begin{tabular}{c c c} \hline \hline  & **RMSE [mm w.e.]** & \(\mathbf{R^{2}}\) \\ \hline GMON CS725\_K, manual & 71.94 & 0.71 \\ GMON CS725\_TL, manual & 91.38 & 0.15 \\ GMON CS725\_K, GNSS & 35.89 & 0.93 \\ GMON CS725\_TL, GNSS & 68.22 & 0.53 \\ manual, GNSS & 65.98 & 0.64 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Statistical comparison of SWE derived by GNSS, two GMON sensors (CS725_K and CS725_TL), and manual snow pits on a weekly basis at the NEIGE testsite at Foret Montmoreny. The range of the SWE validation results presented in this study for the Foret Montmorey are in good accordance with previously conducted studies validating the GNSS in situ SWE component successfully at the high-alpine study site Weissfulhjoch in the Swiss Alps as presented in [PERSON] et al. [11] and [PERSON] et al. [8].