Solar illumination control of ionospheric outflow above polar cap arcs
Solar illumination control of ionospheric outflow above polar cap arcs
We measure the flux density, composition, and energy of outflowing ions above the polar cap, accelerated by quasi-static electric fields parallel to the magnetic field and associated with polar cap arcs, using Cluster. Mapping the spacecraft position to its ionospheric foot point, we analyze the dependence of these parameters on the solar zenith angle (SZA). We find a clear transition at SZA between ?94° and ?107°, with the O+ flux higher above the sunlit ionosphere. This dependence on the illumination of the local ionosphere indicates that significant O+ upflow occurs locally above the polar ionosphere. The same is found for H+, but to a lesser extent. This effect can result in a seasonal variation of the total ion upflow from the polar ionosphere. Furthermore, we show that low-magnitude field-aligned potential drops are preferentially observed above the sunlit ionosphere, suggesting a feedback effect of ionospheric conductivity.
1304-1311
Maes, L.
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Maggiolo, R.
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De Keyser, J.
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Dandouras, I.
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Fear, R.C.
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Fontaine, D.
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Haaland, S.
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12 March 2015
Maes, L.
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Maggiolo, R.
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De Keyser, J.
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Dandouras, I.
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Fear, R.C.
8755b9ed-c7dc-4cbb-ac9b-56235a0431ab
Fontaine, D.
de241387-aef6-450e-8027-198bd5285cd3
Haaland, S.
ff49f62e-6867-4805-a462-bbd609b2e28c
Maes, L., Maggiolo, R., De Keyser, J., Dandouras, I., Fear, R.C., Fontaine, D. and Haaland, S.
(2015)
Solar illumination control of ionospheric outflow above polar cap arcs.
Geophysical Research Letters, 42 (5), .
(doi:10.1002/2014GL062972).
Abstract
We measure the flux density, composition, and energy of outflowing ions above the polar cap, accelerated by quasi-static electric fields parallel to the magnetic field and associated with polar cap arcs, using Cluster. Mapping the spacecraft position to its ionospheric foot point, we analyze the dependence of these parameters on the solar zenith angle (SZA). We find a clear transition at SZA between ?94° and ?107°, with the O+ flux higher above the sunlit ionosphere. This dependence on the illumination of the local ionosphere indicates that significant O+ upflow occurs locally above the polar ionosphere. The same is found for H+, but to a lesser extent. This effect can result in a seasonal variation of the total ion upflow from the polar ionosphere. Furthermore, we show that low-magnitude field-aligned potential drops are preferentially observed above the sunlit ionosphere, suggesting a feedback effect of ionospheric conductivity.
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Maes_et_al-2015-Geophysical_Research_Letters.pdf
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Accepted/In Press date: 12 February 2015
Published date: 12 March 2015
Organisations:
Astronomy Group
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Local EPrints ID: 394178
URI: http://eprints.soton.ac.uk/id/eprint/394178
ISSN: 0094-8276
PURE UUID: ad2bf248-ef4d-4e72-89bb-ee304508ba29
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Date deposited: 12 May 2016 11:24
Last modified: 15 Mar 2024 03:49
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Author:
L. Maes
Author:
R. Maggiolo
Author:
J. De Keyser
Author:
I. Dandouras
Author:
D. Fontaine
Author:
S. Haaland
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