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  Saturn's Nightside Ring Current During Cassini's Grand Finale

Provan, G., Bradley, T., Bunce, E., Cowley, S., Cao, H., Dougherty, M., et al. (2021). Saturn's Nightside Ring Current During Cassini's Grand Finale. Journal of Geophysical Research: Space Physics, 126(3): e2020JA028605. doi:10.1029/2020JA028605.

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Genre: Journal Article

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 Creators:
Provan, G., Author
Bradley, T.J., Author
Bunce, E.J., Author
Cowley, S.W.H., Author
Cao, H., Author
Dougherty, M., Author
Hunt, G.J., Author
Roussos, Elias1, Author           
Staniland, N.R., Author
Tao, C., Author
Affiliations:
1Department Planets and Comets, Max Planck Institute for Solar System Research, Max Planck Society, ou_1832288              

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 MPIS_PROJECTS: CASSINI: MIMI
 MPIS_PROJECTS: CASSINI: LEMMS
 Abstract: During Cassini's Grand Finale proximal orbits, the spacecraft traversed the nightside magnetotail to ∼21 Saturn radii. Clear signatures of Saturn's equatorial current sheet are observed in the magnetic field data. An axisymmetric model of the ring current is fitted to these data, amended to take into account the tilt of the current layer by solar wind forcing, its teardrop-shaped nature and the magnetotail and magnetopause fringing fields. Variations in ring current parameters are examined in relation to external driving of the magnetosphere by the solar wind and internal driving by the two planetary period oscillations (PPOs), and compared with previous dawn and dayside observations. We find that the relative phasing of the PPOs determines the ring current's response to solar wind conditions. During solar wind compressions when the PPOs are in antiphase, a thick partial ring current is formed on the nightside, dominated by hot plasma injected by tail reconnection. This partial ring current should close partly via magnetopause currents and possibly via field-aligned currents into the ionosphere. However, during solar wind compressions when the PPOs are in phase, this partial ring current is not detected. During solar wind rarefactions an equatorial “magnetodisc” configuration is observed in the dayside/dawn/nightside regions, with similar total currents flowing at these local times. During very quiet intervals of prolonged solar wind rarefaction, a thin current sheet with an enhanced current density is formed, indicative of a ring current dominated by cool, dense, Enceladus water group ions.

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Language(s): eng - English
 Dates: 2021
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1029/2020JA028605
 Degree: -

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Title: Journal of Geophysical Research: Space Physics
  Other : JGR-A
  Abbreviation : J. Geophys. Res. - A
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Washington, D.C. : American Geophysical Union
Pages: - Volume / Issue: 126 (3) Sequence Number: e2020JA028605 Start / End Page: - Identifier: ISSN: 0148-0227
CoNE: https://pure.mpg.de/cone/journals/resource/991042728714264