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    Identification of electron field-aligned current systems in Saturn's magnetosphere

    Schippers, P. and André, N. and Gurnett, D.A. and Lewis, Gethyn R. and Persoon, A.M. and Coates, Andrew J. (2012) Identification of electron field-aligned current systems in Saturn's magnetosphere. Journal of Geophysical Research 117 (A5), ISSN 0148-0227.

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    Abstract

    Based on the analysis of 7 years of Cassini electron plasma spectrometer data near Saturn's equatorial plane, we computed the average directional electron current in the Northern and the Southern hemispheres separately. We determined the net current density by subtracting the downward electron current density (equator to the ionosphere) from the upward electron current density (ionosphere to the equator). From the symmetric analysis (no separation in local time), we identified: (1) layers of net upward current carried by the thermal electrons (1–10 eV) in both hemispheres inside 5–8 RS (Saturn Radius = 60,268 km) (region A) and (2) layers of net downward current carried by a population of warmer electrons (10–400 eV) inside 8–10 RS (region B). From the analysis of the currents organized by local time (dayside and nightside parsing), new features were identified such as (1) a day-night asymmetry of the current carried by the warm and hot (400 eV–26,000 eV) electrons beyond 10 RS (region C), and (2) the possible existence of inter-hemispheric currents directed from the Southern to the Northern hemisphere inside 4 RS (region A) and oppositely directed at about 13–15 RS (region C). Our interpretation is that the observed current system results from the superimposition of (1) a current system associated with the corotation enforcement, (2) a current system linked to the presence of the newly identified noon-to-midnight convection electric field and (3) a system of inter-hemispheric currents driven by the thermosphere-ionosphere. We finally discuss the relation of the observed currents with the newly identified Saturn's secondary auroral emissions.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): Field-aligned currents, Saturn, electrons, magnetosphere
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences > UCL/Birkbeck Centre for Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 02 Dec 2014 13:13
    Last Modified: 02 Dec 2014 13:13
    URI: http://eprints.bbk.ac.uk/id/eprint/11149

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