Discovery of Alfvén waves planetward of Saturn's rings

D. J. Southwood; H. Cao; O. Shebanits; Tom Elsden; G. J. Hunt; M. K. Dougherty

doi:10.1029/2020JA028473

Discovery of Alfvén waves planetward of Saturn's rings

D. J. Southwood^*, H. Cao, O. Shebanits, Tom Elsden, G. J. Hunt, M. K. Dougherty

^*Corresponding author for this work

Applied Mathematics

Research output: Contribution to journal › Article › peer-review

Abstract

Between April and September 2017 in the final stages of the Cassini Saturn Orbiter mission the spacecraft executed 22 orbits passing planetward of the innermost ring, the D ring. During all periapsis passes oscillations were detected in the azimuthal magnetic field components on typical time scales of a few minutes. We argue that these time varying magnetic signals detected on the spacecraft are also primarily time varying in the plasma frame. Furthermore, we show that nearly all signals exhibit a spatial feature, namely a magnetic node near the effective field line equator. We propose that the oscillations are associated with Alfvén waves excited in local field line resonances, most likely driven from global sources.

Original language	English
Article number	e2020JA028473
Number of pages	18
Journal	Journal of Geophysical Research: Space Physics
Volume	126
Issue number	2
Early online date	15 Dec 2020
DOIs	https://doi.org/10.1029/2020JA028473
Publication status	Published - 10 Feb 2021

Keywords

Alfven waves
D-ring
Saturn magnetosphere

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10.1029/2020JA028473Licence: CC BY

Southwood_2020_JGR-SP_Discovery_Alfven-waves_CC
Copyright © 2020. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Final published version, 2.5 MBLicence: CC BY

Cite this

@article{653693c3f8ab4ff58a4b7bd8c3b6f2d3,

title = "Discovery of Alfv{\'e}n waves planetward of Saturn's rings",

abstract = "Between April and September 2017 in the final stages of the Cassini Saturn Orbiter mission the spacecraft executed 22 orbits passing planetward of the innermost ring, the D ring. During all periapsis passes oscillations were detected in the azimuthal magnetic field components on typical time scales of a few minutes. We argue that these time varying magnetic signals detected on the spacecraft are also primarily time varying in the plasma frame. Furthermore, we show that nearly all signals exhibit a spatial feature, namely a magnetic node near the effective field line equator. We propose that the oscillations are associated with Alfv{\'e}n waves excited in local field line resonances, most likely driven from global sources.",

keywords = "Alfven waves, D-ring, Saturn magnetosphere",

author = "Southwood, {D. J.} and H. Cao and O. Shebanits and Tom Elsden and Hunt, {G. J.} and Dougherty, {M. K.}",

note = "Funding: Work at Imperial College was supported by UKRI/STFC grants ST/N000692/1 and ST/S000364/1. T. Elsden was funded by a Leverhulme Early Career Fellowship, split jointly by the Leverhulme Trust (ECF-2019-155) and the University of Leicester.",

year = "2021",

month = feb,

day = "10",

doi = "10.1029/2020JA028473",

language = "English",

volume = "126",

journal = "Journal of Geophysical Research: Space Physics",

issn = "2169-9402",

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T1 - Discovery of Alfvén waves planetward of Saturn's rings

AU - Southwood, D. J.

AU - Cao, H.

AU - Shebanits, O.

AU - Elsden, Tom

AU - Hunt, G. J.

AU - Dougherty, M. K.

N1 - Funding: Work at Imperial College was supported by UKRI/STFC grants ST/N000692/1 and ST/S000364/1. T. Elsden was funded by a Leverhulme Early Career Fellowship, split jointly by the Leverhulme Trust (ECF-2019-155) and the University of Leicester.

PY - 2021/2/10

Y1 - 2021/2/10

N2 - Between April and September 2017 in the final stages of the Cassini Saturn Orbiter mission the spacecraft executed 22 orbits passing planetward of the innermost ring, the D ring. During all periapsis passes oscillations were detected in the azimuthal magnetic field components on typical time scales of a few minutes. We argue that these time varying magnetic signals detected on the spacecraft are also primarily time varying in the plasma frame. Furthermore, we show that nearly all signals exhibit a spatial feature, namely a magnetic node near the effective field line equator. We propose that the oscillations are associated with Alfvén waves excited in local field line resonances, most likely driven from global sources.

AB - Between April and September 2017 in the final stages of the Cassini Saturn Orbiter mission the spacecraft executed 22 orbits passing planetward of the innermost ring, the D ring. During all periapsis passes oscillations were detected in the azimuthal magnetic field components on typical time scales of a few minutes. We argue that these time varying magnetic signals detected on the spacecraft are also primarily time varying in the plasma frame. Furthermore, we show that nearly all signals exhibit a spatial feature, namely a magnetic node near the effective field line equator. We propose that the oscillations are associated with Alfvén waves excited in local field line resonances, most likely driven from global sources.

KW - Alfven waves

KW - D-ring

KW - Saturn magnetosphere

U2 - 10.1029/2020JA028473

DO - 10.1029/2020JA028473

M3 - Article

SN - 2169-9402

VL - 126

JO - Journal of Geophysical Research: Space Physics

JF - Journal of Geophysical Research: Space Physics

IS - 2

M1 - e2020JA028473

ER -

Discovery of Alfvén waves planetward of Saturn's rings

Abstract

Keywords

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