UCL Discovery Stage
UCL home » Library Services » Electronic resources » UCL Discovery Stage

The Changing Eigenfrequency Continuum during Geomagnetic Storms: Implications for Plasma Mass Dynamics and ULF Wave Coupling

Wharton, SJ; Rae, IJ; Sandhu, JK; Walach, M; Wright, DM; Yeoman, TK; (2020) The Changing Eigenfrequency Continuum during Geomagnetic Storms: Implications for Plasma Mass Dynamics and ULF Wave Coupling. Journal of Geophysical Research: Space Physics , 125 (6) , Article e2019JA027648. 10.1029/2019ja027648. Green open access

[thumbnail of 2019JA027648.pdf]
Preview
Text
2019JA027648.pdf - Published Version

Download (13MB) | Preview

Abstract

Geomagnetic storms are one of the most energetic space weather phenomena. Previous studies have shown that the eigenfrequencies of closed magnetic field lines in the inner magnetosphere decrease during storm times. This change suggests either a reduction in the magnetic field strength and/or an increase in its plasma mass density distribution. We investigate the changes in local eigenfrequencies by applying a superposed multiple‐epoch analysis to cross‐phase spectra from 132 geomagnetic storms. Six ground magnetometer pairs are used to investigate variations from approximately 3 < L < 7 and across the whole dayside sector. We find that at L > 4, the eigenfrequencies decrease by as much as 50% relative to their quiet time values. Both a decrease in magnetic field strength and an increase in plasma mass density, in some locations by more than a factor of two, are responsible for this reduction. The enhancement of the ring current and an increase in Oxygen ion density could explain these observations. At L < 4, the eigenfrequencies increase due to the decrease in plasma mass density caused by plasmaspheric erosion.

Type: Article
Title: The Changing Eigenfrequency Continuum during Geomagnetic Storms: Implications for Plasma Mass Dynamics and ULF Wave Coupling
Open access status: An open access version is available from UCL Discovery
DOI: 10.1029/2019ja027648
Publisher version: http://dx.doi.org/10.1029/2019ja027648
Language: English
Additional information: Copyright © 2020 The Authors. This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: ULF Waves, Cross‐phase, Geomagnetic, Storms, Plasma, Mass, Density, Eigenfrequencies, Ring, Current
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery-pp.ucl.ac.uk/id/eprint/10098580
Downloads since deposit
1,116Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item