## 3 Results
### A Qualitative Investigation of IBI Events Using Swarm and COSMIC \(n_{e}\) Data
The number of IBIs during the main phase of the super and intense storms is clearly larger than those that occurred during the recovery phase. This enhanced number of IBIs during the main phase is in agreement with previous studies that correlate the occurrence rate of IBIs with the activity level and the main phase of geomagnetic storms [60; 61; 62; 63]. The reason for that is the PPEF, which is transmitted instantaneously into the equatorial region during the convection processes and becomes intensified during the main phase. Therefore, if we expect the PPEF to be the main driver of IBIs observed during the main phases of intense and super storms, another question arises regarding the IBIs observed during the recovery phase of all storms. This indicates the insignificant role of the PPEF in the generation mechanism of the IBIs. Therefore, another mechanism such as the DDEF or the shielding electric field could be the main reason for generating IBIs during the recovery phase of the storms. The geographic coordinates and the altitudes of the noontime hmF2 were recorded for each COSMIC profile. The selected noontime events vary from 12:00 LT to 16:00 LT. Subsequently, the selected data were binned into 10 degrees in latitude and one hour UT, where the median altitudinal and \(n_{e}\) values within this binned area were calculated as shown in the middle and lower rows of Figure 10, respectively. Results indicate that, the ionospheric hmF2 varies with respect to the type of geomagnetic storm. The hmF2 was observed to be strongly raised to high altitudes only within the main phase of the super storm, but through the whole recovery phase, it was observed at lower altitudes, while during the moderate storm it was always observed at higher altitudes. The hmF2 of super and intense storms was similar, which was always observed at lower altitudes in comparison with moderate storms. Also, the hmF2 was larger in the northern hemisphere during super storm and strongly shifted poleward from the equator. The large altitudes of the northern hemispheric hmF2 during super storms could be attributed to the trans\(-\)equatorial wind, which flows from the summer (northern) hemisphere to the winter (southern) hemisphere and subsequently raises the hmF2 to large altitudes in the summer/northern hemisphere. During intense and moderate geomagnetic storms, the hmF2 is centered on the equator. The reason for this is that, both storms are observed within the autumn equinox. The \(n_{e}\) profile corresponding to the three types of storms in the lower row shows strong depletion of \(n_{e}\) during super storms in comparison with moderate storms, while in intense storms, it exhibits an intermediate state. Also, the double crests due to the equatorial ionization anomaly in both hemispheres appeared clearly during the moderate geomagnetic storm (panel in the rightmost bottom) and disappeared during super storms (panel in the leftmost bottom). Figure 10.— Rows from top to bottom correspond to the Dst index in nT, a contour map of the hnr2 (km), and a contour map of the value of the \(n_{r}\) (cm\({}^{-3}\)) at the hnr2, respectively. Columns from left to right correspond to super, intense, and moderate geomagnetic storms observed on 21 June 2015; 12 October 2016; and 12 September 2014, respectively.