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    Auroral electron precipitation and flux tube erosion in Titan’s upper atmosphere

    Snowden, D. and Yelle, R.V. and Galand, M. and Coates, Andrew J. and Wellbrock, Anne and Jones, Geraint H. and Lavvas, P. (2013) Auroral electron precipitation and flux tube erosion in Titan’s upper atmosphere. Icarus 226 (1), pp. 186-204. ISSN 0019-1035.

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    Abstract

    Cassini data shows that Titan’s atmosphere strongly depletes the electron content in Saturn’s flux tubes, producing features known as electron bite-outs, which indicate that the flux of auroral electrons decreases over time. To understand this process we have developed a time-dependent two-stream model, which uses field line geometries and drift paths calculated by a three-dimensional multi-fluid model of Titan’s plasma interaction. The boundary conditions of the model account for the time-dependent reduction or increase in electron flux along Saturn’s magnetic field lines because of the loss or production of electrons in Titan’s atmosphere. The modification of the auroral electron flux depends on the electron bounce period in Saturn’s outer magnetosphere; therefore, we also calculate electron bounce periods along several Kronian field lines accounting for both the magnetic mirroring force and the field-aligned electric potential in Saturn’s plasma sheet. We use the time-dependent two-stream model to calculate how the reduction in the auroral electron flux affects electron impact ionization and energy deposition rates in Titan’s upper atmosphere. We find that the flux of higher energy (>>50 eV) electrons entering Titan’s atmosphere is strongly reduced over time, resulting in smaller ionization and energy deposition rates below ∼1300 km altitude. Finally, we show that sample spectrograms produced from our calculations are consistent with CAPS-ELS data.

    Metadata

    Item Type: Article
    Additional Information: Titan, Atmosphere, Aeronomy
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences > UCL/Birkbeck Centre for Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 05 Jun 2013 11:05
    Last Modified: 11 Sep 2013 13:55
    URI: http://eprints.bbk.ac.uk/id/eprint/7239

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