On magnetospheric electron impact ionisation and dynamics in Titan's ram-side and polar ionosphere – a Cassini case study

K. Agren (1) , J.-E. Wahlund (1) , Ronan Modolo (1) , D. Lummerzheim (2) , M. Galand (3) , I. Müller-Wodarg (3) , P. Canu (4) , W. S. Kurth (5) , T. E. Cravens (6) , R. V. Yelle (7) , J. H. Waite (8) , A. J. Coates (9) , G. R. Lewis (9) , D. T. Young (10) , C. Bertucci (3) , M. K. Dougherty (3)

1 IRF - Swedish Institute of Space Physics [Uppsala / Kiruna]
2 Geophysical Institute [Fairbanks]
3 Space and Atmospheric Physics Group [London]
4 CETP - Centre d'étude des environnements terrestre et planétaires
5 Department of Physics and Astronomy [Iowa City]
6 Department of Physics and Astronomy [Lawrence, Kansas]
7 LPL - Lunar and Planetary Laboratory [Tucson]
8 AOSS - Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor]
9 MSSL - Mullard Space Science Laboratory
10 SwRI - Southwest Research Institute [San Antonio]

We present data from the sixth Cassini flyby of Titan (T5), showing that the magnetosphere of Saturn strongly interacts with the moon's ionosphere and exo-ionosphere. A simple electron ionisation model provides a reasonable agreement with the altitude structure of the ionosphere. Furthermore, we suggest that the dense and cold exo-ionosphere (from the exobase at 1430 km and outward to several Titan radii from the surface) can be explained by magnetospheric forcing and other transport processes whereas exospheric ionisation by impacting low energy electrons seems to play a minor role.

Domaines: Océan, Atmosphère; Astrophysique stellaire et solaire [astro-ph.SR]; Planétologie et astrophysique de la terre [astro-ph.EP]

K. Agren, J.-E. Wahlund, Ronan Modolo, D. Lummerzheim, M. Galand, et al.. On magnetospheric electron impact ionisation and dynamics in Titan's ram-side and polar ionosphere – a Cassini case study. Annales Geophysicae, 2007, 25 (11), pp.2359-2369. ⟨10.5194/angeo-25-2359-2007⟩. ⟨hal-00330154⟩