## 3 Results
### Three-Satellite Constellation  
This simulation consists of an LEO constellation of three satellites orbiting in a 45-degree inclination plane at an elevation of 500 km. The three satellites are separated by two minutes. Each satellite carries a polarimetric-capable RO receiver with a receiving antenna capable of collecting GNSS telemetry data within a 45\({}^{\circ}\) antenna azimuth range (relative to boresight), capable of tracking both rising and setting occultations from the GPS and GLONASS satellites. Each RO is characterized by the location of the tangent point when the straight line between the transmitter and the receiver is 100 km below the surface, corresponding roughly to a ray grazing the surface. For the purpose of this study, the choice of straight-line tangent height is unimportant since the locations of simulated RO do not depend sensitively on the height. The RO captured by these three satellites have been simulated for 30 consecutive days and then repeated to complete a full year. A precession of \(-3\) deg/day is included in the simulations of the satellite's orbits to obtain a realistic sampling over the Earth. With this configuration, around 1.2E6 occultations are obtained over the course of one year. Note that this quantity stands for possible occultations, but no spacecraft duty cycle nor processing losses are taken into account. An RO _event_ is defined as a clustered group of near-simultaneous occultations, which happen when the different  
Figure 5: A picture of the Cion RO receiver instrument flying onboard the CICERO 6U-sized cubesats (right), shown alongside the size of the larger TriG receiver (left) flying onboard each of the six satellites in the COSMIC-2 constellation. satellites obtain an RO from the same GNSS transmitter. Such events can be complete (the three satellites capture an RO from the same transmitter within a few minutes), or non-complete (one or two of the three satellites miss or truncate an RO tracking opportunity). This latter condition typically happens when the transmitted GNSS ray path is oriented in such a way that it is received near the edge of the antenna pattern (e.g., \(>\)45\({}^{\circ}\) antenna azimuth), and the occultation falls outside the azimuth cutoff threshold, as implemented in the occultation scheduler. Considering events instead of individual ROs, over one year, 400,000 events are captured, and 97% of these are complete events (i.e., all three satellites capture an RO from the same GNSS transmitter). A sample of where these clusters of RO appear when projected onto the Earth is shown in Figure 6, where only those RO events that have crossed the extreme precipitation are shown. Heavy and extreme precipitation is defined when the cumulative differential phase shift (defined as \(\Delta\phi\)) exceeds 2 mm and 6 mm, respectively (discussed further in Section 3.1.1). In this one-day scenario, 1173 (about 0.1% of the total) events are shown. Note that the RO locations from this train of satellites tend to clump together, increasing the likelihood that one or more observations fall inside and outside the regions of heavy precipitation. Further analysis of Figure 6 shows that this configuration yields events with different RO orientation geometries. Depending on the location of the transmitter and the azimuth at which the signal arrives to the receiver, the separation distance between the three RO tangent points can change, as well as the time difference separating each of the ROs. This condition can be exploited to achieve sampling of convection and its environment over a range of separations. The distribution of these separations is further explored in Figure 7. Figure 7a shows the frequency distribution (histograms) of the distance between the RO tangent points obtained by two different combinations of satellites in the train (first versus second and first versus third), and Figure 7b shows the histogram of the corresponding time difference.