The response of Saturn's dawn field-aligned currents to magnetospheric and ring current conditions during Cassini's proximal orbits: evidence for a Region 2 response at Saturn
File(s)Hunt et al FAC RC (March 2022).pdf (3.23 MB)
Accepted version
Author(s)
Type
Journal Article
Abstract
Cassini's 2017 proximal orbits provided the opportunity to examine the auroral field-aligned currents in the northern hemisphere dawn sector in relation to wider magnetospheric conditions. We combine three recent studies to examine the response of the dawn region auroral field-aligned currents and the azimuthal ring currents to compressions and expansions of the Saturnian magnetosphere. For compressions of Saturn's magnetosphere resulting in tail reconnection, the currents within the downward current sheet, located equatorward of the main auroral oval, increases in strength with increasing total ring current and location of the peak downwards current moves inwards toward Saturn. While the inverse relation occurs during intervals of quiet or expanded magnetospheric conditions. During compression events there is an increase in the energetic particle intensities, in particular in the protons (35–506 keV), within the downward current region. This current system is akin to an Earth-like “region 2” field aligned current within Saturn's magnetosphere, with tail reconnection occurring when the magnetosphere is compressed resulting in a partial nightside ring current closed by a downward current near to dawn. Within the upward current sheet, mapping to Saturn's main auroral oval, both non-rotating subcorotating current and the rotating Planetary Period Oscillations (PPOs) currents flow. The upward current is strongly modulated by the PPOs but also increases in strength, with enhanced high-energy protons, during intervals of magnetospheric compressions and tail reconnection. We conclude that the enhanced plasma injected into the midnight-dawn sector during tail reconnection events results in an enhanced subcorotation current system.
Date Issued
2022-06-01
Date Acceptance
2022-05-25
Citation
Journal of Geophysical Research: Space Physics, 2022, 127 (6), pp.1-15
ISSN
2169-9380
Publisher
American Geophysical Union
Start Page
1
End Page
15
Journal / Book Title
Journal of Geophysical Research: Space Physics
Volume
127
Issue
6
Copyright Statement
© 2022. American Geophysical Union. All Rights Reserved. This is the accepted version of the following article: Hunt, G. J., Provan, G., Bradley, T. J., Cowley, S. W. H., Dougherty, M. K., & Roussos, E. (2022). The response of Saturn's dawn field-aligned currents to magnetospheric and ring current conditions during Cassini's proximal orbits: Evidence for a region 2 response at Saturn. Journal of Geophysical Research: Space Physics, 127, which has been published in final form at https://doi.org/10.1029/2021JA029852
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000810497200001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
Saturn
magnetosphere
field-aligned currents
current systems
magnetospheric dynamics
SOLAR-WIND
Publication Status
Published
Article Number
ARTN e2021JA029852
Date Publish Online
2022-06-03