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    Magnetospheric period oscillations at Saturn: Comparison of equatorial and high-latitude magnetic field periods with north and south Saturn kilometric radiation periods

    Andrews, D.J. and Coates, Andrew J. and Cowley, S.W.H. and Dougherty, M.K. and Lamy, L. and Provan, G. and Zarka, P. (2010) Magnetospheric period oscillations at Saturn: Comparison of equatorial and high-latitude magnetic field periods with north and south Saturn kilometric radiation periods. Journal of Geophysical Research: Space Physics 115 (A12), ISSN 0148-0227.

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    Abstract

    It has recently been shown using Cassini radio data that Saturn kilometric radiation (SKR) emissions from the Northern and Southern hemispheres of Saturn are modulated at distinctly different periods, ∼10.6 h in the north and ∼10.8 h in the south, during the southern summer conditions that prevailed during the interval from 2004 to near-equinox in mid-2009. Here we examine Cassini magnetospheric magnetic field data over the same interval and show that two corresponding systems of magnetic field oscillations that have the same overall periods, as the corresponding SKR modulations, to within ∼0.01% are also present. Specifically, we show that the rotating quasi-dipolar field perturbations on southern open field lines and the rotating quasi-uniform field in the inner region of closed field lines have the same period as the southern SKR modulations, although with some intervals of slow long-term phase drift of unknown origin, while the rotating quasi-dipolar field perturbations on northern open field lines have the same period as the northern SKR modulations. We also show that while the equatorial quasi-uniform field and effective southern transverse dipole are directed down tail and toward dawn at southern SKR maxima, as found in previous studies, the corresponding northern transverse dipole is directed approximately opposite, pointing sunward and also slightly toward dawn at northern SKR maxima. We discuss these findings in terms of the presence of two independent high-latitude field-aligned current systems that rotate with different periods in the two hemispheres.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): magnetospheric period oscillations, SKR, magnetic field
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences > UCL/Birkbeck Centre for Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 10 Dec 2014 14:02
    Last Modified: 10 Dec 2014 14:02
    URI: http://eprints.bbk.ac.uk/id/eprint/11264

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