Excitation of large amplitude compressional ULF waves in the magnetosphere by solar wind pressure spikes and IMF southward turning
Author(s)
Type
Journal Article
Abstract
We present a case study of large amplitude, compressional Pc5 waves observed by GOES 13 and 15 at geosynchronous orbit near noon. These waves were excited near the arrival time of two consecutive solar wind dynamic pressure spikes at the magnetopause, the second of which was associated with a large and rapid southward turning of the Interplanetary Magnetic Field (IMF). Magnetopause oscillations at a similar frequency were observed by the THEMIS spacecraft in the post-noon magnetosphere, however without clear signatures of compressional waves. The analysis of the ground response near the GOES foot-points, located close to the Churchill line of magnetometer stations, revealed an increase in wave power following each spike, with slight changes in polarizations. Following the second pressure spike's arrival at the magnetosphere, we found evidence of Field Line Resonances in the Northward component of the magnetic field, which suggests coupling with the compressional waves observed at GOES. We investigated potential Ultra Low Frequency drivers, and identified the most likely driving mechanism to be the drift-mirror instability; lack of appropriate measurements however prevented us from confirming this hypothesis.
Date Issued
2026-08-01
Date Acceptance
2026-07-09
Citation
Journal of Geophysical Research: Space Physics, 2026, 131 (8)
ISSN
2169-9380
Publisher
American Geophysical Union (AGU)
Journal / Book Title
Journal of Geophysical Research: Space Physics
Volume
131
Issue
8
Copyright Statement
© 2026 The Author(s). Journal of Geophysical Research: Space Physics published by Wiley Periodicals LLC on behalf of American Geophysical Union. 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.
License URL
Publication Status
Published
Article Number
e2025JA035007
Date Publish Online
2026-07-29