## 2 Experimental Facilities and Data  
We used the ISTP SB RAS facilities to comprehensively study small-scale irregularities. We employed the S4 index [31] to study amplitude scintillations and \(\sigma\varphi\)[32] to study phase scintillations. We used the spread-F [33] width to study irregularities within the ionosonde wavelength range. The S4 index is the signal intensity \(E\) standard deviation normalized to the average signal intensity:  
\[S4=\frac{\sqrt{\left\langle E^{2}\right\rangle-\left\langle E\right\rangle^{2}}} {\left\langle E\right\rangle}. \tag{1}\]  
The \(\sigma\varphi\) index is simply the carrier phase \(\varphi\) standard deviation:  
\[\sigma\varphi=\sqrt{\left\langle\varphi^{2}\right\rangle-\left\langle\varphi \right\rangle^{2}}. \tag{2}\]  
The spread-F width is the measure of trace broadening on an ionogram near the ionosphere peak. Below, we describe the instruments and data:  
(1) Ionosonde DPS-4 [34] enabled us to measure the spread-F width. We used the ionosonde located in Irkutsk - IR352 (52.3\({}^{\circ}\)N, 104.3\({}^{\circ}\)E; red star in Figure 1), at -48\({}^{\circ}\) magnetic latitude. We manually scaled the ionograms to obtain the spread-F width. The ionosonde antenna is not typical. This did not enable us to measure the directions of signal receiving. During the geomagnetic storm, the ionosonde in Irkutsk was operating with a 15-min cadence. Additionally, we analyzed data from the ionosondes in Norilsk--NO369 (69.4\({}^{\circ}\)N, 88.1\({}^{\circ}\)E), Yakutsk--YA462 (62.0\({}^{\circ}\)N, 129.7\({}^{\circ}\)E), Mohe--MH453 (52.0\({}^{\circ}\)N, 122.5\({}^{\circ}\)E), and Moscow--MO155 (55.47\({}^{\circ}\)N, 37.3\({}^{\circ}\)E). As the ionosonde records the spread-F within -3-10 Mhz at 200-300 km, the irregularities that primarily affect the ionosonde signal have sizes 2.5-5 km. (2) Irkutsk Incoherent Scatter Radar (IISR) [35]. The IISR is located next to Irkutsk (52.9\({}^{\circ}\)N, 103.3\({}^{\circ}\)E; red star in Figure 1), at -49\({}^{\circ}\) magnetic latitude. Its radiation pattern center is at 52.6\({}^{\circ}\)N, 102.9\({}^{\circ}\)E. The IISR receivers enabled us to measure scintillations of discrete space radio sources, when they crossed the radar sector of view [21]. In our experiments, we recorded the Cygnus A signal. Cygnus A is the most powerful radio galaxy in our part of the Universe. Cygnus A emits in a broad frequency band including the IISR frequency band (154-162 Mhz). We should note that the radiation pattern is  
Figure 1: Locations of Irkutsk Incoherent Scatter Radar/Irkutsk ionosonde DPS-4 (red star) and GPS/GLONASS receivers (blue dots). shown for the chosen frequency. By changing the frequency, we changed the radiation pattern, and thus could track the radio source [21]. Unfortunately, during the storm, the IISR was operating in passive mode. So, we have no corresponding electron density profiles or ion velocities. The highest temporal resolution for measurements in the passive mode is of the order of seconds. We used the 4.5-s resolution data. The integration time for the S4 index calculation is 1 minute. Since the IISR operates at ~150 MHz, at 100-300 km, the size of the irregularities primarily affecting the IISR signal amplitude is 400-800 m.  
(3) GPStation-6 specialized GPS/GLONASS receiver. The receiver is located in Irkutsk (52.3\({}^{\circ}\)N, 104.3\({}^{\circ}\)E; red star in Figure 1), at ~48\({}^{\circ}\) magnetic latitude. GPStation-6 receiver enabled us to measure the amplitude scintillations intensity, S4, and phase variations, \(\sigma\varphi\)[36]. The data sampling rate used for the S4 and \(\sigma\varphi\) calculation is 50 Hz (0.02-s resolution). The integration time for the S4 and \(\sigma\varphi\) is 1 minute. The S4 and \(\sigma\varphi\) measured by GPStation-6 were transformed into equivalent vertical values [37]. The GPStation-6 receives signals within the L1 and L2 bands for all the GPS/GLONASS satellites. There is an option with some satellites to receive a third frequency band, L5 and L3 for GPS and GLONASS, respectively.