## 3 Results  
For the set of colocations between COSMIC-2 RO and two ionosondes corresponding to the high-rate sounding campaigns in October 2022 and March 2024, we analyzed EDPs derived using two independent techniques with the data processing steps and selection criteria described in the previous sections. The analysis was performed not only by comparison of the F2 layer peak values derived from colocated EDPs, but also the shape of density distribution on the bottomside sections of the profiles from the observation lower limit to the F2 layer peak. In order to avoid Abel inversion related uncertainties in the absolute values of COSMIC-2 RO EDPs, each RO profile has been adjusted to match the unbiased F2 peak density values obtained from the colocated ionogram closest in time. This process was made separately for the Ebre and El Arenosillo ionosonde colocations. Such techniques are often used to calibrate EDPs derived from the incoherent scatter radar soundings when critical frequency measurements from a nearby ionosonde are applied to adjust the incoherent scatter radar plasma density profile [50, 51]. As a result, we selected high-quality data products for the representative local time intervals corresponding to the geomagnetically quiet ionospheric conditions at moderate (October 2022) and high (March 2024) solar activity levels. While our result descriptions primarily focused on Ebre ionosonde observations, data from El Arenosillo was analyzed as well. Figure 4 illustrates several representative cases with the colocation events between COSMIC-2 RO and Ebre ionosonde EDPs in October 2022 (Day-Of-Year (DOY) 297-299). Figure 5 shows similar results, but for March 2024 (DOY 079-080). For each event, we combined the ionogram recordings and colocated EDP comparisons. The GNSS RO observations from LEO satellites do not provide redundant EDPs over the same locations daily, but as we mentioned before, the high-rate HF sounding campaigns provide opportunities to assess more colocation events due to the larger number of available ionograms within a time window. As a result, we can obtain precise RO-ionosonde EDP colocations for various local time conditions. In Figure 4a, we present the case of the closest-in-time colocation between two COSMIC-2 RO EDPs and time sequences of the Ebre ionosonde ionograms. Here, we have two COSMIC-2 occultations with a GLONASS R01 transmitter at ~15:20 UT on DOY 297, 2022, and with GPS G23 one minute later at ~15:21 UT that day. There are 1-min sequence ionosonde ionograms (15:19-15:22 UT, local daytime conditions) matching in time with these RO EDPs (three ionograms are placed on the top part of Figure 4a). The lower panel in Figure 4a displays COSMIC-2 RO EDPs (black lines) for these two cases overlaid on EDPs derived from the Ebre ionogram inversions (color lines, color corresponded to different sounding times). These results correspond to the afternoon ionosphere with well-developed daytime ionospheric layers. The COSMIC-2 RO and ionosonde profiles closely match near the F2 ionization peak by shape, and both techniques show the location of the F2 peak at an altitude of ~290 km. In the bottom section of all profiles, there are recognized E and F1 ionosphere layers, although some differences exist. The COSMIC-2 RO profiles show a more structured altitudinal density distribution within a 100-170 km range. These differences can be due to limitations in HF soundings, specifically in the E-F valley region where reflections from less dense upper layers cannot be obtained (e.g., [52]). Other panels (b-d) in Figure 4 present cases of EDP colocations between COSMIC-2 RO and ionosonde for different local time conditions. The local time for the Ebre and El Arenosillo ionosonde locations is UTC + 01. Figure 4b corresponds to the pre-sunset hours (~17 LT) when both ionosonde and RO techniques show a decreasing of plasma density in the bottomside ionosphere and an absence of the developed E and F1 ionosphere layers.