## 4 Results and Discussion
However, it should be emphasised that EGNOS system users are informed about the decrease in EGNOS positioning quality within a maximum of 6 s, and the maximum error for the KIRU station did not exceed 7.36 m. To sum up, it can be concluded that the EGNOS model against the other three solutions (off, Klob, NeQuick) is clearly the best considering the accuracy of horizontal positioning reaching an average value for the stations considered of about 0.75 m. The differences between off, Klob, and NeQuick are not significantly distinct from each other, and the average mean error for these solutions reached a value of 1.34 m.  
The results of vertical position error (VPE) are graphically shown in Figure 7, and the numerical values are summarised in Table 2 on the right. Similar to horizontal positioning, the largest fluctuations in accuracy were obtained for the KIRU station. This is especially visible for the off solution, which achieves clearly worse accuracy in the first four analysed days. Interestingly, the positioning in the last three days of the examined period was clearly worse for the Klob model. In the off solution, diagrams clearly show daily cycles of vertical positioning accuracy, while for solutions using ionosphere models, this phenomenon is almost imperceptible. Clearly, the worst results were obtained for the off solution, where the average error values ranged from 4.36 m (KIRU) to 3.02 (ISTA), reaching an average value for the three stations of 3.47 m. Results that were twice as good were obtained for solutions with the Klob and NeQuick models; for these models, the average error reached 1.50 m, and the NeQuick solution turned out to be slightly better than that of Klob. Similarly to the horizontal results, \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & **KIRU** & **LAMA** & **ISTA** & & **KIRU** & **LAMA** & **ISTA** \\ \hline \multirow{3}{*}{off} & HPE\_max & 14.43 & 4.32 & 5.87 & \multirow{3}{*}{off} & VPE\_max & 23.41 & 9.77 & 10.35 \\  & HPE\_st\_dev. & 1.13 & 0.58 & 0.92 & & VPE\_st\_dev. & 2.98 & 1.54 & 1.91 \\  & HPE\_mean & 1.45 & 1.39 & 1.42 & & VPE\_mean & 4.36 & 3.03 & 3.02 \\ \hline \multirow{3}{*}{Klob} & HPE\_max & 6.55 & 3.65 & 4.71 & \multirow{3}{*}{Klob} & VPE\_max & 11.99 & 6.07 & 6.60 \\  & HPE\_st\_dev. & 0.77 & 0.51 & 0.73 & & VPE\_st\_dev. & 1.56 & 0.90 & 1.07 \\  & HPE\_mean & 1.25 & 1.33 & 1.23 & & VPE\_mean & 2.00 & 1.17 & 1.60 \\ \hline \multirow{3}{*}{NeQuick} & HPE\_max & 9.32 & 3.24 & 4.70 & \multirow{3}{*}{NeQuick} & VPE\_max & 9.72 & 7.22 & 5.63 \\  & HPE\_st\_dev. & 0.97 & 0.43 & 0.62 & & VPE\_st\_dev. & 1.36 & 1.06 & 0.90 \\  & HPE\_mean & 1.78 & 1.18 & 1.01 & & VPE\_mean & 1.79 & 1.42 & 1.03 \\ \hline \multirow{3}{*}{EGNOS} & HPE\_max & 7.36 & 3.14 & 4.23 & \multirow{3}{*}{EGNOS} & VPE\_max & 15.63 & 5.75 & 8.40 \\  & HPE\_st\_dev. & 0.36 & 0.20 & 0.38 & & VPE\_st\_dev. & 0.81 & 0.52 & 0.59 \\ \cline{1-1}  & HPE\_mean & 0.57 & 0.96 & 0.74 & & VPE\_mean & 0.94 & 1.16 & 0.68 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The results of horizontal (left) and vertical (right) accuracy parameters at examined stations in meters. the vertical positioning accuracy for the EGNOS model proved to be the best, achieving an excellent average value of 0.93 m. Looking at the results for the EGNOS model graphically, it seems that the LAMA station came out the best, but when analysing the numerical results, it turns out that the average error for the LAMA station was the biggest. At the LAMA station, unlike KIRU and ISTA, no sharp jumps in accuracy were observed, and the maximum error reached only 5.75 m. At the KIRU and ISTA stations, the maximum errors for the EGNOS model reached the values of 15.63 and 8.40 m, respectively; at these stations, there was a clear decrease in accuracy on 8 September. These high values of errors for the EGNOS model occurred during the climactic periods of the geomagnetic storm and coincide exactly with the peak values of the AE-index.