## 3 Results
### ROTI and GNSS Precise Point Positioning Accuracy Maps  
We estimated the ionospheric TEC, ROTI, and positioning for the full 5 days but only show 6 hours per day. On the eclipse day, we observe the largest positioning variations during this time window (around P1-P4 time, see Figure 5). This study focuses on the positioning accuracy of the stations during the 10 June 2021 annular solar eclipse, during the time between 8 and 14 UT. We estimated the PPP-AR using the CSRS-PPP service, as described in Section 2.4. Comparing the eclipse day with respect to the DoYs 159 and 160, we can see that the percentage of GNSS stations that exceeded maximum 3D positioning error \(\geqslant\)10 cm and 3D-RMS \(\geqslant\)3 cm (positioning thresholds) jumped from \(\sim\)180 (\(\sim\)8%) to 333 (\(\sim\)14%) and from \(\sim\)170 (\(\sim\)7%) to 210 (\(\sim\)9%), respectively. In addition, the ROTI threshold \(\geqslant\)0.25 TECu/min was taken according to [PERSON] et al. [36], and used in the methodology [29]. Figure 6 shows maximum 3D positioning errors, 3D-RMS of the apparent position, and ROTI maps, for each of the five selected DoYs. Figure 4: Ionospheric behavior using Swarm-A measurements. (**Upper panels**) present ionospheric TEC data taken by Swarm-A satellite at 850 km (at 400 km above the Swarm-A). The TEC gathered through the satellite orbit is presented over an Earth map (left panel) and as a profile with data obtained in one of the comparison days (write panel). The three satellite passes are from 45\({}^{\circ}\)S to \(\sim\)90\({}^{\circ}\)N, from left to right, between \(\sim\)11.70–12.40, \(\sim\)10.10–10.80, and \(\sim\)8.50–9.20 UT during 2 days before eclipse day (DoY 159), and eclipse day (DoY 161). The annular eclipse path at 450 km (grey line) and 850 km altitude (magenta line) are also shown on DoY 161. VTEC on DoY 161 (red dots) compared to DoY 159 (green dots) between \(\sim\)11.70–12.40 UT, \(\sim\)10.10–10.80 UT, and \(\sim\)8.50–9.20 UT. (**Bottom panels**) depict Swarm-A in situ electron density (\(N_{e}\)) presented in the same way than the VTEC data. ROTI was calculated as described in Section 2.2 to study the relationship between the variation of TEC and the positioning error for the eclipse. The images in the Figure 6 (right panel) show five maps of ROTI, each representing the stations that had ROTI greater than 0.25 TECu/min. Each map represents a different day, but at the same time as that of the solar eclipse, DoYs 160-163 between 8 and 14 UT. We do not show the maps for DoY 159 because they are similar to those for DoY 160. The TEC data (e.g., Figure 3) and the derived PPP-AR (see Figure 6 (left panels)), and Figure 7) show that there are two regions where the errors are more severe during the solar eclipse (DoY 161, between 8 and 14 UT). These regions are Greenland and South America. For this reason, we focused this study on these sectors. Figure 5: Time variations of the percentage of stations with 3D positioning error greater than 10 cm on DoY 161. The (**left panel**) shows the 36 GNSS stations localized in Greenland. The (**right panel**) presents the 335 GNSS stations that are situated in South America. Figure 6: Maximum 3D positioning errors \(\geqslant\)10 cm (**left panels**); and ROTI \(\geqslant\)0.25 TECu/min (**right panels**) between 8 and 14 UT. From top to bottom shows DoYs 160–163. Annular eclipse path at ground level (blue line), and at 350 km of altitude (magenta line) are also shown. In the Greenland and South America regions, we can find 36 (\(\sim\)2%) and 335 (\(\sim\)14%) of the 2337 total available GNSS stations, respectively. We determined the percentage of stations localized in both regions that had errors that fell at certain intervals during the time period of the annular eclipse (between 8 and 14 UT). Figure 7 shows the percentages of stations that meet the thresholds of maximum 3D positioning error, 3D-RMS, and ROTI.