## 4 Discussion
### Ionospheric Behavior  
The present analysis aims to show, as best as currently possible, the effects that the solar eclipse generates both in the ionosphere under the moon's shadow as well as in the global ionosphere. The relevance of this event is that there are few of them that occur in polar regions, in this case, in the Arctic. We have used interpolated global maps from TEC and we have calculated the difference between eclipse and reference days. The results of the TEC maps show a significant reduction under the moon's shadow, except at the CN00 station that has similar behavior to the LMMF, CN57, BOAV, and MSBL stations (see Figures 3 and 8, Table 1); the GNSS stations located in the region of the eclipse reaching a maximum of \(\tau\) = 1 to 288 min, A peak \(\sim\)\(-\)5 TECu, A[%] = \(-\)61 to \(-\)27%. Table 1 details these parameters for GNSS stations of some selected regions (see Figure 1). The values of these parameters agree with those obtained for the solar eclipses of 9 March 1997 solar eclipse [4; 22], 1 August 2008 [10], and 20 March 2015 [5; 23]. TEC depletion was not as pronounced in the MAG0, TIXI, and YAKT stations (A[%] = \(-\)38 to \(-\)30%) compared to others GNSS stations (A[%] = \(-\)61 to \(-\)40%) with a similar percentage of obscuration (\(\sim\)88%). This could be due to the fact that the sunset in MAG0, TIXI, and YAKT stations happened during the time-window of the eclipse at ground level. Moreover, the other stations were closer to the greatest eclipse (see Figures 1 and 8, Table 1). In addition to the decrease of TEC in the ionosphere under the Moon's shadow, we have observed interesting and significant effects far from that region. This is the case of a significant decrease in TEC that seems to move southward from the shadow, passing through the North Atlantic, and remaining stationary for several hours over the Caribbean and the north of Brazil, at the stations CN00, LMMF, CN57, BOAV, PIFL, MSBL (see Figures 3 and 8, and Table 1). The delay value relative to GE time was between \(\sim\)30 and \(\sim\)168 min, A peak \(\sim\)\(-\)11 TECu, A[%] = \(-\)65 to \(-\)28%, \(\Delta\)T \(>\) 10 h. This area coincides with the location of the crests of EIA. The TEC variations were more intense north and south of the magnetic equator, where they were similar to those obtained at the GNSS stations located in the eclipse region. On the other hand, applying \(DVTEC_{t}-DVTECnew_{t}\), we observed that the mean was between \(-\)0.5 and 0.1 TECu; and standard deviation was less than 0.7 TECu. Therefore,TEC changes due to the weak geomagnetic activity during the DoY 162, did not cause problems in the ionospheric TEC background to our presented results for the eclipse day (see Supplementary Materials, Figure S2, Table S1). In order to verify the negative disturbance in TEC on EIA crests, we have compared them with ionosonde observations of the sector involved (Figure 10). The Ramey (RA, 18.5\({}^{\circ}\)N, 67.1\({}^{\circ}\)W) station on the Caribbean side, and Sao Luis (SL, 2.6\({}^{\circ}\)S, 44.2\({}^{\circ}\)W), Fortaleza (FZ, 3.9\({}^{\circ}\)S, 38\({}^{\circ}\)W) and Cachoeira Paulista (CP, 22.7\({}^{\circ}\)S, 45.0\({}^{\circ}\)W) stations on the Brazil side were selected. The geographic locations of these stations are indicated with blue rhombuses in Figure 1. The data is obtained from the Digital Ionogram Data Base ([[http://giro.uml.edu/didbase/scaled.php](http://giro.uml.edu/didbase/scaled.php)]([http://giro.uml.edu/didbase/scaled.php](http://giro.uml.edu/didbase/scaled.php)), accessed on 4 August 2021) [50]. As a result, Figure 10 shows coherence between TEC and the critical frequency of the plasma (foF2) of each station. That is, the electron concentration after the eclipse maximum (\(\sim\)11 UT) decreases (red circles) with respect to the reference curve (black line) calculated as indicated in Section 2.1. These same changes can be seen in the height of maximum electron concentration (hmF2).