## 4 Results and Discussion
### PlanetQi Observations Spatial and Temporal Distribution  
Figure 3 depicts the worldwide distribution of ROE for the three satellites within the PlanetQi constellation throughout the entire study duration. GN02, GN03, and GN04 have operational periods lasting 198, 55, and 28 days, respectively, with average daily occurrences of 1099, 1313, and 1843 ROE. The global coverage is consistently uniform, excluding the Polar Regions and a specific area delineated by 30\({}^{\circ}\) to 50\({}^{\circ}\) longitude and 40\({}^{\circ}\) to 60\({}^{\circ}\) latitude. The higher number of RO events in GN02 compared to GN03 and GN04 could be influenced by several factors. These may include differences in satellite configurations and orbits, which affect the spatial and temporal distribution of observations. Instrument sensitivity variations between satellites might also contribute to the observed differences in RO event counts. Additionally, the locations of GNSS transmitters with respect to LEO satellite locations can affect the availability of occultation events, leading to variability in the number of observations from each satellite [33]. Figure 4 illustrates the geographic distribution of each LEO satellite, considering both latitude and longitude tracking. It is noteworthy that the operational duration of GN02 exceeds that of GN03 and GN04 by approximately 3.5 and 7 times, respectively, throughout the entire study period. All LEO satellites exhibit extensive observational coverage within the latitude range of \(10^{\circ}\) to \(30^{\circ}\) and \(-20^{\circ}\) to \(-50^{\circ}\), with moderate and limited distribution coverage observed at the Equator and the poles, respectively. The distribution along the longitude is predominantly uniform, except for a specific region around \(30^{\circ}\) longitude, where there is a notable deficit in observation coverage. Interestingly, there is a slight increase in observation numbers in western longitudes compared to eastern longitudes within this deficient region. The distribution of observations throughout the day, as depicted in Figure 5, reveals that the twelfth hour boasts the highest total number of observations compared to other hours, while the twenty-third hour exhibits the lowest. Specifically for GN02, the eighth hour registers the maximum total number of observations, contrasting with the minimum observed in the twenty-third hour. In the case of LEO GN03, the thirteenth hour records the maximum number of observations, whereas the third hour records the minimum. Similarly, for LEO GN04, the twelfth hour sees the highest number of observations, and the nineteenth  
Figure 3: Global distribution of PlanetQ ROE through the study period based on LEO satellites. hour reflects the minimum. The overall occurrence of observations is nearly uniform across the day hours, except for variations in hours 0, 3, 22, and 23. Figure 6 depicts the daily occurrence of observations for each GNSS satellite. Each GNSS constellation is represented by distinct color bars, and the distribution is based on the average number of observations solely during their operational days. Overall, the average occurrence of observations for all GNSS satellites is relatively uniform, with the maximum diff. in occurrence numbers not exceeding 5 observations. Notably, GO1 and E01 in GPS and Galileo, respectively, exhibit comparatively lower average daily observation numbers. To specify, the average daily number of observations for GPS, Galileo, GLONASS, and Beidou satellites amounts to 440, 413, 392, and 489 ROE/day, respectively. The notable increase in the number provided by the Beidou constellation can be attributed to its synchronization of operating days with those of both GN02 and GN04. Figure 7 shows the total occurrence of RO events along the latitude and the longitude referencing the observation GNSS transmitter constellation.