## 3 Results and Analyses
sudden recovery, approximately 5 days, reaching mean values of 15 TECU at the SSC on 19 February, at the SSC on 20 February, and approximately 24 h after the SSC on 23 February. The corresponding TEC variations from the GNSS stations (Figure 5e-i) follow similar patterns of TEC variability, with clear differences, most probably caused by local irregularities, where plasma is differently distributed during the different phases of the storms as compared to the averaged character of the IGS TEC. For the northern EIA crest, the rTEC enhancements exceeded 60% at the NKLLG station on 19 February, which clearly coincides with the responses of the IGS TEC. This is also slightly appreciable in the southern EIA crest for the RABT station. Moreover, on the SSC event of 20 February, a clear enhancement appeared at both GNSS stations in the dip equator region (CLBR and BKFP); this corresponded with the response of the IGS profile. Here, there was an observation of the depletion after the rapid recovery in the MAL2 station, which matches with the low TEC values of the southern IGS profile. On the contrary, at the dip equatorial region on 20 February, the CLBR and BKFP GNSS stations showed clear enhancements following a long period of an enhanced TEC at the IGS profile, which lasted with several peaks until 24 February. The variability in the merging electric field \(\mathrm{E_{m}}\) is associated with the variability in the PPEF (Figure 8b), mostly for all the SSCs and the HSSW events during the main phases of the storms. Although the storm on 20 February was stronger than that on 15 February, these featured a similar PPEF variation, with amplitudes of approximately 0.25 mV/m. However, the EEJ illustrated maximal development starting from the SSC along the storm main phase  
Figure 7: Low latitude GIMs TEC differences between the IRI-2012 model and the PCA-based model set for quiet conditions (Am = 6). The differences are along the (**a**) southern and (**b**) northern EIA crests (\(\pm\)15\({}^{\circ}\)) and along (**c**) the magnetic equator, from 10 to 28 February 2014. The profiles used to extract TEC are shown in Figure 5b. The bottom panel (**d**) shows the mean values along the (**a–c**) profiles. The SSCs and HSSW are highlighted with vertical yellow and green lines, respectively. (Figure 8d). The EEJ largely varied during 19 and 20 February, with less intensity the rest of the period, reaching values of \(-100\) nT, and with an amplitude of 150 nT during \(\sim\)12 h after the SSCs. This is the effect of the disturbance dynamo. At the beginning of the storm, there was only PPEF at the equator, and, after several hours, the DDEF was acting at the equator. Figure 9 shows a global perspective of the magnetosphere-ionosphere variations caused by the multiphase storm of February 2014. The ASY-D and ASY-H indices correlate with the Am index (Figure 9b). The GEC index shows the dynamics of the ionosphere as a whole during the storms [56]. This figure also includes the current Intensity CI variations at the different regions (Figure 9c,d) and the total CI (Figure 9e). Finally, the IGS TEC profiles are shown at the bottom of this figure. All the global variables shown in Figure 9  
Table 1.0 Upper atmosphere variability during the February 2014 storm at the African region. From top to bottom, (**a**) the merging electric field E\({}_{\rm m}\), (**b**) the dPPEF at Africa, (**c**) SYM-H, Am, Dst indices, (**d**) the dEEJ at Africa, (**e–i**) the TEC variations measured by GNSS stations in Figure 2, and (**h**) the GIMs TEC differences between the IGS products and the PCA-based model set for quiet conditions (Am = 6) at the EIA crests and at the magnetic equator (from Figure 5a). The (**e–i**) GNSS stations are classified in terms of the proximity to the (**j**) EIA crests and magnetic equator profiles. The SSCs and HSSW are highlighted with vertical yellow and green lines, respectively. reflect the SSCs and HSSW events. All the variables peaked at 0:00 UT on 16 February.