Electron Density Distributions in Saturn's Ionosphere

A. M. Persoon (1) , W. S. Kurth (1) , D. A. Gurnett (1) , J. B. Groene (1) , A. H. Sulaiman (1) , J.‐ E. Wahlund (2) , M. W. Morooka (2) , Lina Hadid (2) , A. F. Nagy (3) , J. H. Waite Jr. (4) , T. E. Cravens (5)

1 University of Iowa [Iowa City]
2 IRF - Swedish Institute of Space Physics [Uppsala / Kiruna]
3 AOSS - Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor]
4 SwRI - Southwest Research Institute [San Antonio]
5 Department of Physics and Astronomy [Lawrence, Kansas]

Between 26 April and 15 September 2017, Cassini executed 23 highly inclined Grand Finale orbits through a new frontier for space exploration, the narrow region between Saturn and the D Ring, providing the first opportunity for obtaining in situ ionospheric measurements. During the Grand Finale orbits, the Radio and Plasma Wave Science instrument observed broadband whistler mode emissions and narrowband upper hybrid frequency emissions. Using known wave propagation characteristics of these two plasma wave modes, the electron density is derived over a broad range of ionospheric latitudes and altitudes. A two-part exponential scale height model is fitted to the electron density measurements. The model yields a double-layered ionosphere with plasma scale heights of 545/575 km for the northern/southern hemispheres below 4,500 km and plasma scale heights of 4,780/2,360 km for the northern/southern hemispheres above 4,500 km. The interpretation of these layers involves the interaction between the rings and the ionosphere.

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]; Physique des plasmas [physics.plasm-ph]

A. M. Persoon, W. S. Kurth, D. A. Gurnett, J. B. Groene, A. H. Sulaiman, et al.. Electron Density Distributions in Saturn's Ionosphere. Geophysical Research Letters, 2019, 46 (6), pp.3061-3068. ⟨10.1029/2018GL078020⟩. ⟨hal-02640930⟩