Research output: Contribution to Journal/Magazine › Literature review › peer-review
Research output: Contribution to Journal/Magazine › Literature review › peer-review
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TY - JOUR
T1 - Sources of local time asymmetries in magnetodiscs
AU - Arridge, C. S.
AU - Kane, M.
AU - Sergis, N.
AU - Khurana, K. K.
AU - Jackman, C. M.
N1 - Date of Acceptance: 11/03/2015
PY - 2015/4
Y1 - 2015/4
N2 - The rapidly rotating magnetospheres at Jupiter and Saturn contain a nearequatorial thin current sheet over most local times known as the magnetodisc, resembling a wrapped-up magnetotail. The Pioneer, Voyager, Ulysses, Galileo, Cassini and New Horizons spacecraft at Jupiter and Saturn have provided extensive datasets from which to observationally identify local time asymmetries in these magnetodiscs. Imaging in the infrared and ultraviolet from ground-and space-based instruments have also revealed the presence of local time asymmetries in the aurora which therefore must map to local time asymmetries in the magnetosphere. Asymmetries are found in (i) the configuration of the magnetic field and magnetospheric currents, where a thicker disc is found in the noon and dusk sectors; (ii) plasma flows where the plasma flow has local time-dependent radial components; (iii) a thicker plasma sheet in the dusk sector. Many of these features are also reproduced in global MHD simulations. Several models have been developed to interpret these various observations and typically fall into two groups: ones which invoke coupling with the solar wind (via reconnection or viscous processes) and ones which invoke internal rotational processes operating inside an asymmetrical external boundary. In this paper we review these observational in situ findings, review the models which seek to explain them, and highlight open questions and directions for future work.
AB - The rapidly rotating magnetospheres at Jupiter and Saturn contain a nearequatorial thin current sheet over most local times known as the magnetodisc, resembling a wrapped-up magnetotail. The Pioneer, Voyager, Ulysses, Galileo, Cassini and New Horizons spacecraft at Jupiter and Saturn have provided extensive datasets from which to observationally identify local time asymmetries in these magnetodiscs. Imaging in the infrared and ultraviolet from ground-and space-based instruments have also revealed the presence of local time asymmetries in the aurora which therefore must map to local time asymmetries in the magnetosphere. Asymmetries are found in (i) the configuration of the magnetic field and magnetospheric currents, where a thicker disc is found in the noon and dusk sectors; (ii) plasma flows where the plasma flow has local time-dependent radial components; (iii) a thicker plasma sheet in the dusk sector. Many of these features are also reproduced in global MHD simulations. Several models have been developed to interpret these various observations and typically fall into two groups: ones which invoke coupling with the solar wind (via reconnection or viscous processes) and ones which invoke internal rotational processes operating inside an asymmetrical external boundary. In this paper we review these observational in situ findings, review the models which seek to explain them, and highlight open questions and directions for future work.
KW - Saturn
KW - Jupiter
KW - Magnetodisc
KW - Local time asymmetry
KW - Plasma flows
KW - Current sheet
KW - Solar wind interaction
KW - Reconnection
KW - Kelvin-Helmholtz
KW - SATURNS INNER MAGNETOSPHERE
KW - JOVIAN MAGNETOSPHERE
KW - JUPITERS MAGNETOSPHERE
KW - MAGNETIC-FIELD
KW - ELECTRIC-FIELD
KW - SOLAR-WIND
KW - EQUATORIAL CURRENT
KW - CURRENT SHEET
KW - RING CURRENT
KW - FLOWS
U2 - 10.1007/s11214-015-0145-z
DO - 10.1007/s11214-015-0145-z
M3 - Literature review
VL - 187
SP - 301
EP - 333
JO - Space Science Reviews
JF - Space Science Reviews
SN - 0038-6308
IS - 1-4
ER -