## 2 Dataset
### An Example of Ionospheric Irregularities  
At first, we give an example of ionospheric irregularities near the equator observed by Swarm A during 19:30-19:48 universal time (UT) on 12 October 2021, and the responses of multiple parameters to the irregular structures are shown in Figure 1. Figure 1a displays the electron density (Ne), background density (bNe), and detrended density (detNe) in orange, blue, and yellow, respectively. The double-peak equatorial ionization anomaly (EIA) can be clearly identified during 19:39-19:45 UT. Additionally, there were many ionospheric irregularities, as the electron density oscillated dramatically (mainly from 19:32 to 19:39 and from 19:43 to 19:45 UT) predominantly at the poleward sides of the EIA. By removing the background, it can be seen that the signature of the large-scale EIA structure can be mitigated or ignored, while the small-scale irregularities are reserved. Figure 1: An example of the derived irregularity parameters from Swarm A as a function of UT on 21 December 2021. (**a**) electron density (Ne, red), background electron density (bNe, blue), and the detrended electron density (detNe, orange), (**b**) ROD and RODI, (**c**) detrended TEC, (**d**) ROTI, (**e**) detrended SNR, (**f**) S4c, (**g**) geomagnetic latitude and geographic latitude. Figure 1b plots the ROD and RODI in blue and orange lines, respectively. To present the amplitude of the electron density fluctuations straightly, only the absolute values of ROD are shown here. The two parameters well reflected the dramatic changes in density observed in Figure 1a. For example, a slight fluctuation in electron density can be observed around 19:42 UT within the EIA region in Figure 1a, which is more obvious in detrended Ne; correspondingly, an apparent fluctuation of ROD and RODI can be seen at the same position in Figure 1b. Previous studies developed different algorithms for automatic detection of those irregularities [14; 23; 24]. A key strategy of those algorithms is that, by setting the thresholds of the fluctuation amplitude, the fluctuations can be determined whether they are strong enough to be considered irregularities, rather than noises. Those thresholds can be generally categorized into two types: absolute and relative density perturbations. Previous studies pointed out that the occurrence pattern of the irregularities determined by the absolute density perturbation definition exhibited better agreement with that of the scintillations [25]. Since this work is dedicated to cross-check the in situ plasma irregularities with scintillation events, we then adopt the absolute enhancement/attenuation threshold in the density to detect the ionospheric irregularities. Thus, to avoid the trend of background density like EIA, \(RODI>10^{4}\) cm\({}^{-3}\)/s is set as the threshold for determining the ionospheric irregularities. Based on the experiments (not shown) during data processing, if the threshold is set with the fluctuation within \(\pm 30\%\), it has little impact on the statistical results, which indicates the reliability of the threshold selection. To evaluate the radio signal quality during its transmission through the irregularities, we calculate the phase and amplitude scintillation parameters from the TEC and signal-to-noise ratio (SNR). The vertical TEC is first converted from the STEC calculated by the GPS observation data from the onboard receiver, and the vertical TEC data are detrended by subtracting the mean value in 20 s in each arc, as shown in Figure 1c. In addition, we exclude the data as the GPS satellites flew at elevation angles below 30 degrees. The parameters derived from TEC data show similar oscillations in the corresponding positions, as shown in Figure 1b. Note that these parameters represent TEC fluctuations in the topside ionosphere, and a value of 0.1 is used as the threshold of ROTI to indicate the strong phase scintillation.