## 2 Data and Methods
### Penetration Electric Fields, Equatorial Electrojet, and Current Intensity  
The PPEF was retrieved from the electric field model for geomagnetism developed by the Cooperative Institute for Research in Environmental Sciences at University of Colorado Boulder (Boulder, CO, USA) ([[http://geomag.colorado.edu](http://geomag.colorado.edu)]([http://geomag.colorado.edu](http://geomag.colorado.edu)), accessed date: 1 September 2021). PPEF indicates magnetospheric disturbance as an interplanetary motional electric field appears in Earth's ionosphere, and it is inserted by the solar wind into the magnetosphere. We estimated the PPEF at different longitudinal sectors to show the ionospheric responses during the February 2014 multiphase geomagnetic storm. The model uses the frequency-dependent transfer function to estimate the PPEF in the equatorial ionosphere due to interplanetary electric field [49; 50]. PPEF has different phases: (1) direct penetration [28], (2) shielding phase [51], and (3) overshielding phase [52]. The EEJ strength was calculated using the procedure of [53], where the data used are from the same stations in the American, African, and Asian sectors. The geomagnetic stations are listed in Table 2, and the EEJ strength is estimated by the following equation [54]:  
\[\text{EEJ}=\Delta\text{H}_{\text{eq}}-\Delta\text{H}_{\text{off\_eq}} \tag{3}\]  
In this equation, \(\Delta\text{H}_{\text{eq}}\) and \(\Delta\text{H}_{\text{off\_eq}}\) are the differential horizontal magnetic field intensity (transient variation) for the stations at the equatorial dip region and outside the equatorial region, respectively. Here, H represents the contributions of Earth's core field, the lithosphere field, and the transient variation related to external electric current, in this \begin{table}
\begin{tabular}{c c c c c c} \hline
**Code** & **Name** & **Country** & **Latitude (\({}^{\circ}\))** & **Longitude (\({}^{\circ}\))** & **MLat (\({}^{\circ}\))** \\ \hline NKLG & N\({}^{\prime}\)Koltang & Gabon & 0.35 & 9.67 & \(-\)8.04 \\ MAL2 & Malindi & Kenya & \(-\)2.99 & 40.19 & \(-\)12.42 \\ CLBR & Calabar & Nigeria & 4.95 & 8.35 & \(-\)4.29 \\ RABT & Rabat & Morocco & 33.99 & 353.14 & 23.88 \\ BKFP & Kebbi & Nigeria & 12.46 & 4.22 & 0.63 \\ \hline \end{tabular}
\end{table} 
Table 1: Coordinates and details of the GNSS stations. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Code** & **Name** & **Country** & **Latitude (\({}^{\circ}\))** & **Longitude (\({}^{\circ}\))** & **MLat (\({}^{\circ}\))** \\ \hline HUA & Huancayo & Peru & \(-\)12.07 & \(-\)75.22 & \(-\)1.80 \\ TRW & Trelew & Argentina & \(-\)43.25 & \(-\)65.30 & \(-\)33.05 \\ AEE & Addis Ababa & Ethiopia & 9.04 & 38.77 & 0.18 \\ NAB & Nairobi & Kenya & \(-\)1.16 & 36.48 & \(-\)10.65 \\ LKW & Langkawi & Malaysia & 6.30 & 99.78 & \(-\)2.32 \\ HLN & Hualien & Taiwan & 23.9 & 121 & 16.86 \\ \hline \end{tabular}
\end{table} 
Table 2: Geomagnetic observatories for EEJ estimation. case, the EEJ strength. Then, the stations used to retrieve EEJ strength for the American, African, and Asian sectors are calculated as follows:  
\[\left\{ \begin{array}{c}\text{EEJ at America }\rightarrow\text{ EEJ}(\text{ HUA})=\Delta\text{H}(\text{ HUA})-\Delta\text{H}(\text{TRW})\\ \text{EEJ at Africa }\rightarrow\text{ EEJ}(\text{AEE})=\Delta\text{H}(\text{AEE})-\Delta \text{H}(\text{NAB})\\ \text{EEJ at Asia }\rightarrow\text{ EEJ}(\text{LKW})=\Delta\text{H}(\text{LKW})-\Delta \text{H}(\text{HLN})\end{array} \right. \tag{4}\]  
The solar-quiet current intensity (CI) is estimated using the geomagnetic stations listed in Table 3. For the CI estimation, a baseline of D (declination) magnetic component values is firstly obtained by averaging hourly data centered on the local midnight data, i.e., 23 h \(\leq\) LST \(\leq\) 2 h. Then, CI at night is assumed negligible due to the low electron density, and it results in an extremely low electric conductivity (e.g., [55]).