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| Titel |
Time Variability of Titan's Ionosphere Revisited |
| VerfasserIn |
Jen-Kai Hsu, Wing-Huen Ip, Rebecca Perryman, Hunter Waite |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108299
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| Publikation (Nr.) |
 EGU/EGU2015-8050.pdf |
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| Zusammenfassung |
| Since the Saturn Orbital Insertion in 2004, the Ion Neutral Mass Spectrometer (INMS)
experiment aboard the Cassini-Huygens spacecraft has acquired an extensive data set. The
decadal coverage of the measurements during numerous close encounters with Titan allows
the study of spatial and temporal variations of Titan’s nitrogen-rich atmosphere above
1000-km altitude.
Titan’s ionosphere is quite different to that of Earth’s ionosphere. Due to Titan’s thick
(hundreds of kilometers) and dense atmosphere, the measurable ion density of Titan’s
nightside ionosphere extends well beyond the terminator. The diurnal variation of the ion
density profiles and compositional changes are the result of photoionization and
magnetospheric electron ionization (important at the night side). The different time
evolutions of the light and heavy species from day to night could be indicative of the effects
of flow dynamics and ion-molecule chemistry. From the observations, we can determine the
ion content in Titan’s night-side and the asymmetry between the dawn and dusk ion density
profiles.
We have also found in the long term data base the signature of the equatorial expansion of
Titan’s atmosphere during solar maximum. In addition the global distributions of the major
compound N2 and minor species like CH4 and H2 all exhibit significant changes over a solar
cycle as the closest approach points of Cassini moved from the northern hemisphere to the
southern hemisphere.
In this work, we will first compare the diurnal variations between different ion species and
simulate the ion densities to study the possible contributing factors. Then we will
compare the results of our analysis to those reported by other groups to construct a
comprehensive model of Titan’s neutral atmosphere and ionosphere under different solar
conditions. |
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