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Rotational modulation and local time dependence of Saturn's infrared H3+ auroral intensity

Badman, S. V. and Andrews, D. J. and Cowley, S. W. H. and Lamy, L. and Provan, G. and Tao, C. and Kasahara, S. and Kimura, T. and Fujimoto, M. and Melin, H. and Stallard, T. and Brown, R. H. and Baines, K. H. (2012) Rotational modulation and local time dependence of Saturn's infrared H3+ auroral intensity. Journal of Geophysical Research, 117 (A9). ISSN 0148-0227

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    Abstract

    Planetary auroral emissions reveal the configuration of magnetospheric field-aligned current systems. In this study, Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations of Saturn's pre-equinox infrared H3+ aurorae were analysed to show (a) rotational modulation of the auroral intensity in both hemispheres and (b) a significant local time dependence of the emitted intensity. The emission intensity is modulated by the ‘planetary period’ rotation of auroral current systems in each hemisphere. The northern auroral intensity also displays a lesser anti-phase dependence on the southern rotating current system, indicating that part of the southern current system closes in the northern hemisphere. The southern hemisphere aurorae were most intense in the post-dawn sector, in agreement with some past measurements of auroral field-aligned currents, UV aurora and SKR emitted power. A corresponding investigation of the northern hemisphere auroral intensity reveals a broader dawn-noon enhancement, possibly due to the interaction of the southern rotating current system with that of the north. The auroral intensity was reduced around dusk and post-midnight in both hemispheres. These observations can be explained by the interaction of a rotating field-aligned current system in each hemisphere with one fixed in local time, which is related to the solar wind interaction with magnetospheric field lines.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research
    Additional Information: ©2012. American Geophysical Union. All Rights Reserved
    Uncontrolled Keywords: aurora ; field-aligned currents ; magnetosphere
    Subjects:
    Departments: Faculty of Science and Technology > Physics
    ID Code: 67078
    Deposited By: ep_importer_pure
    Deposited On: 10 Oct 2013 11:00
    Refereed?: Yes
    Published?: Published
    Last Modified: 24 Nov 2017 05:29
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/67078

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