Cowley et al Saturn plasma sheet PPOs theory (JGR Jan 2017).pdf (2.4 MB)
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Evidence for periodic variations in the thickness of Saturn's nightside plasma sheet

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journal contribution
posted on 22.05.2017, 15:04 by M. F. Thomsen, C. M. Jackman, Stanley William Herbert Cowley, X. Jia, M. G. Kivelson, G. Provan
During certain portions of the Cassini mission to Saturn, Cassini made repeated and periodic crossings of the magnetospheric current sheet that lies near the magnetic equator and extends well down the magnetospheric tail. These repeated crossings are part of the puzzling set of planetary period variations in numerous magnetospheric properties that have been discovered at Saturn. During 2010 these periodic crossings often display asymmetries such that the northbound crossing occurs faster than the southbound crossing or vice versa, while at other times the crossings are more symmetric. The character of the crossings is well organized by the relative phase of the northern versus southern perturbation currents inferred in earlier analyses of the magnetic field observations. Further, the dependence of the character of the crossings on the relative phase is consistent with similar asymmetries predicted both by the dual rotating current systems inferred from magnetic field observations and by global MHD models that incorporate the effects of hypothesized atmospheric vortices. The two models are themselves in generally good agreement on those predictions. In both models the asymmetries are attributable to a periodic thickening and thinning of the magnetospheric current sheet, combined with a periodic vertical flapping of the sheet. The Cassini observations thus provide additional observational support to such current systems as a likely explanation for many of the known magnetospheric planetary period variations.

History

Citation

Journal of Geophysical Research: Space Physics, 2017, 122 (1), pp. 280-292

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Journal of Geophysical Research: Space Physics

Publisher

American Geophysical Union (AGU)

issn

2169-9380

eissn

2169-9402

Acceptance date

16/11/2016

Copyright date

2016

Available date

22/05/2017

Publisher version

http://onlinelibrary.wiley.com/doi/10.1002/2016JA023368/abstract

Language

en