## 3 Results
### The Occurrence Rate of IBIs during Different Types of Geomagnetic Storms  
Figure 2 presents a global distribution of IBI events observed by Swarm satellites, occurring during different types of geomagnetic storms with respect to the criteria set in Section 2. IBIs observed during super, intense, and moderate geomagnetic storms are shown in the top, middle, and lower panels, respectively. Events observed by Swarm A, B, and C satellites are marked in red, blue, and cyan dots, respectively. The dashed line marked in magenta color on the world map indicates the \(\pm\)20\({}^{\circ}\) latitude from the dip equator, which is marked in the solid magenta line. We noticed that regardless of the few IBIs spread farther from the \(\pm\)20\({}^{\circ}\) latitudinal limits, the majority of IBIs were observed closer to or centered around the dip equator. Also, during moderate storms, no IBIs were observed poleward from the \(\pm\)20\({}^{\circ}\) latitudinal limits. In addition, the IBIs observed during moderate and super storms spread over a large range of longitude in comparison with the majority of IBIs during intense storms, which were concentrated within limited longitudes (20\({}^{\circ}\) W-90\({}^{\circ}\) W). The right column of Figure 2 shows the number of IBIs in the northern and southern hemispheres in magenta and black bars respectively. The range of the Y-axis in both super and intense storms is 15, while for the \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Start Date** & & **Duration** & **Storm** & **Dst** & \\ \hline
**Year** & **Month** & **Day** & **(Days)** & **Type** & **(nT)** & **Number of IBIs** & **Storm Driver** \\ \hline
2018 & 5 & 5 & 9 & Moderate & \(-\)56 & 1 & Solar wind stream \\
2018 & 9 & 10 & 7 & Moderate & \(-\)60 & 0 & CME \\
2018 & 11 & 4 & 11 & Moderate & \(-\)53 & 1 & CME \\
2018 & 4 & 19 & 8 & Moderate & \(-\)66 & 0 & CME \\
2018 & 10 & 7 & 7 & Moderate & \(-\)53 & 0 & CME \\
2019 & 8 & 4 & 8 & Moderate & \(-\)50 & 0 & CME \\
2019 & 5 & 10 & 4 & Moderate & \(-\)51 & 0 & CME \\
2019 & 5 & 13 & 3 & Moderate & \(-\)65 & 0 & CME \\
2020 & 2 & 17 & 10 & Moderate & \(-\)52 & 0 & Negative IMF Bz \\
2020 & 4 & 20 & 2 & Moderate & \(-\)59 & 0 & CME \\
2020 & 7 & 23 & 5 & Moderate & \(-\)52 & 0 & CME \\ \hline \end{tabular}
\end{table} 
Table 2: _Cont._moderate storm it is expanded to 150 because of the large number of IBIs during moderate storms. We noticed that, 64% of intense storms have a large number of IBI events in the southern hemisphere (Figure 2). In contrast, 59% of moderate and super storms have large IBI events in the northern hemisphere. The number of IBIs in the northern hemisphere is slightly larger than that in the southern hemisphere, at all longitudes, during super, intense, and moderate geomagnetic storms. Consequently, the dramatic increase in the number of IBIs during intense storms within 45\({}^{\circ}\) W longitude in the southern hemisphere could be due to the fewer number (36) of IBI events that may mislead the statistical trend. Swarm B orbits the Earth at higher altitudes (~520) km than Swarm A and C, which orbit the Earth at an average altitude of ~420 km; therefore, the probability of observing IBIs during different types of storms at different altitudes is worth investigation. Figure 3a-c displays the number of IBI events observed by the three Swarm satellites with respect to the geographic longitude during distinct types of storms. The red, blue, and cyan bars correspond to IBIs observed by Swarm A, B, and C satellites, respectively. This shows that during super and intense storms, the number of IBIs at the altitudes of Swarm B (~500 km) is larger than those observed at the altitudes of Swarm A and C. Swarm B recorded about 60% of all the events during super and intense storms and 16% during moderate storms. In contrast, during moderate geomagnetic storms, the number of IBI events observed by Swarm A and C is always larger than those detected by Swarm B as shown in Figure 3c.