Midlatitude and high‐latitude electron density profiles in the ionosphere of Saturn obtained by Cassini radio occultation observations

Abstract

[1] Nineteen new radio occultations of the ionosphere of Saturn have been obtained since 2006. Sixteen of these occultations were from midlatitude and high latitudes and thus provided important, new information of the ionosphere for these regions. A high degree of variability in the electron densities were observed, but grouping and averaging the observations as low-, middle-, and high-latitude ones clearly showed that the electron densities increase with latitude. The topside scale heights also indicate small increases with latitude, but these changes are small enough so these increases may not be statistically significant.

Saturn ring rain: Model estimates of water influx into Saturn’s atmosphere

“…In fact, the ring rain water influxes from this work lead to a mid-633 latitude trend in electron density -a decrease with increasing latitude -that is counter to what 634 has been observed (Kliore et al, 2009). There are a number of possible explanations for this 635 fact.…”

“…Connerney and Waite, 1984). One alternative explanation is that SEDs may be sampling 577 the sharp low-altitude ionospheric layers frequently seen in radio occultation electron density 578 profiles Kliore et al, 2009) rather than the canonical ionospheric peak. Such 579 layers are consistent with the presence of gravity waves in Saturn's lower thermosphere 580 (Matcheva and Barrow, 2012), and can lead to narrow regions of electron density enhancements 581 without requiring any additional sources of ionization (Barrow and Matcheva, 2013) Observations of H 3 + allow for a significantly improved indirect estimate of external 597 oxygen influx at Saturn, as they can provide an extended latitude distribution of H 3 + column 598 densities in a single snapshot.…”

Current Systems in Planetary Magnetospheres and Ionospheres

“…At Saturn, using the set of occultation data provided by the Cassini Radio Science experiment, some general trends have been established by, e.g., Kliore et al (2009). There appears to be a tendency for the peak in ionospheric density to increase with increasing latitude.…”

“…Both direct shadowing by the rings and influx of water from the rings to the conjugate ionosphere are suggested by the data. Figure 11 (from Kliore et al 2009) shows average density profiles for three different latitude ranges. An increase of the peak electron density with increasing latitude is clearly evidenced.…”

“…11 Average ionospheric electron density profiles determined from Cassini radio occultation measurements near dawn and dusk within three latitude ranges. From Kliore et al (2009) accumulate charges in specific regions, thus generating electric potential drops between different regions, or be connected to permanent sources of electric potential difference, like the solar wind when the planetary field is reconnected with interplanetary field lines (e.g., Sect. 4.1 below).…”