# Ionospheric Weather at Two Starlink Launches during Two-Phase Geomagnetic Storms
## 2 Data Processing Results
The Starlink S-49 launch at 13:11 UT on 7 July (thick vertical line) occurred two hours later than the storm onset which is close to the 1 st peak of the proton density (Np = 56.84 cm\({}^{-3}\) at 11:25 UT on 7 July). The geomagnetic storm shows gradual development during 15 h of the main phase ending with the 1 st peak SYM-H = \(-\)85 nT at 02:15 UT on 8 July, and the 2 nd less intense peak was observed with SYM-H = \(-\)42 nT at 11:35 UT on 8 July. The gradual development of the geomagnetic storm is accompanied by a quiet GIM-W index (Figure 2b, at 00:00 and 12:00 UT on 7 July). The positive GIM-W enhancement is dominant around the peak of SYM-H (00:00 UT on 8 July), then it is confined at the southern hemisphere towards the storm recovery of SYM-H at 12:00 UT on 8 July. The increased negative W index effects in the northern hemisphere are gradually replaced by the negative storm in the southern hemisphere. Again, these GIMs can be used only for the postprocessing analysis, because they are produced with a lag of 1-2 days from the relevant GIM-TECs. While we observe the local or regional features of the near-Earth plasma on the global GIMs, an advantage of the global electron content (\(GEC\)) is the presentation of the state and variability of the ionosphere as a whole. At a given time, the global electron content depends on 3-D electron density distribution, in terms of latitude, longitude and height, integrated over the volume of the ionosphere and plasmasphere from the surface of the Earth to the altitude of GPS satellites [25]. Calculation of the \(GEC\) proxy is based on GIM-TEC maps available in latitude \(\varphi\) from 87.5\({}^{\circ}\) S to 87.5\({}^{\circ}\) N in steps of \(\Delta\varphi\) = 2.5\({}^{\circ}\), longitude \(\lambda\) from 180\({}^{\circ}\) W to 180\({}^{\circ}\) E in steps of \(\Delta\lambda\) = 5\({}^{\circ}\). Individual grid values \(TEC\) (\(\varphi_{i}\), \(\lambda_{j}\)) from GIM are used to produce \(GEC\) with Equation (1):  
\[GEC=\sum_{i}S_{i}(\varphi_{i})\sum_{j}TEC\big{(}\varphi_{i},\lambda_{j}\big{)} \tag{1}\]  
The surface area coefficient \(S_{i}(\varphi_{i})\) for the cells centered at grid [\(\varphi_{i}\), \(\lambda_{j}\)] depends on latitude \(\varphi_{i}\) and step in longitude \(\Delta\lambda\):  
\[S_{i}(\varphi_{i})=(R_{E}+h)^{2}\cdot|\Delta\lambda|\cdot|\sin(\varphi_{1})- \sin(\varphi_{0})| \tag{2}\]  
with  
\[\varphi_{1}=\varphi_{i}+\frac{\Delta\varphi}{2},\ \ \varphi_{0}=\varphi_{i}-\frac{ \Delta\varphi}{2}\]  
The coefficients are determined according to the geocentric distances of the \(TEC\) receiver and the ionospheric pierce point (in our case, the Earth's radius \(R_{E}\) = 6370 km plus height \(h\) = 450 km). The total number of coefficients \(S_{i}(\varphi_{i})\) is equal to 71 (\(\varphi_{i}\) = \(-\)87.5, \(-\)85, \(\ldots\), 87.5\({}^{\circ}\) N), which are calculated a priori and applied with Equation (1) to different GIMs. Hour-by-hour _GEC_ calculations with the above equations from the hourly UPC tomographic-kriging GIM 'UQRG' (0, 1,..., 23 UT) for February 2022 (Figure 3a) and July 2022 (Figure 3b) reveal two features of _GEC_ variation: (i) missing diurnal _GEC_ variation because the local time changes are masked by latitudinal--longitudinal map summation (Equations (1) and (2)); (ii) appreciable periods of enhanced/depleted _GEC_. The Starlink launches (marked with a star) are observed during the moderate geomagnetic storms (denoted with white lines). Every pixel in the images of Figure 3a,b is derived from a separate GIM, so that _GEC_ presents a metrics reducing the GIM's data set by the number of pixels in one GIM, i.e., 5112 times based on the information in the paper. Daily-hourly _GEC_ variation produced from the different GIMs during February 2022 are plotted in Figure 4a-d. The variation of geomagnetic Apo index equivalent to the Kp index but on an hourly cadence [30] and Dst index [31] during February 2022 are plotted in Figure 4e,f, respectively. The Starlink S-36 launch is shown with a thick vertical line.