Planetary period oscillations in Saturn's magnetosphere: Examining the relationship between abrupt changes in behavior and solar wind-induced magnetospheric compressions and expansions
File(s)
Author(s)
Provan, G
Tao, C
Cowley, SWH
Dougherty, MK
Coates, AJ
Type
Journal Article
Abstract
We examine planetary period oscillations (PPOs) observed in Saturn's magnetospheric magnetic field data from the time of Saturn's equinox in 2009. In particular, we focus on the time period commencing February 2011, when the oscillations started to display sudden and unexpected changes in behavior at ~100–200 day intervals. These were characterized by large simultaneous changes in the amplitude of the northern and southern PPO systems, together with small changes in period and jumps in phase. Nine significant abrupt changes have been observed in the postequinox interval to date, commencing as the Sun started to emerge from a long extended solar minimum. We perform a statistical study to determine whether these modulations in PPO behavior were associated with changes in the solar and/or upstream solar wind conditions. We report that the upstream solar wind conditions show elevated values of solar wind dynamic pressure and density around the time of PPO behavioral transitions, as opposed to before and after these times. We suggest that abrupt changes in PPO behavior may be related to significant changes in the size of the Saturnian magnetosphere in response to varying solar wind conditions.
Date Issued
2015-11-21
Date Acceptance
2015-10-11
Citation
Journal of Geophysical Research: Space Physics, 2015, 120 (11), pp.9524-9544
ISSN
2169-9402
Publisher
American Geophysical Union
Start Page
9524
End Page
9544
Journal / Book Title
Journal of Geophysical Research: Space Physics
Volume
120
Issue
11
Copyright Statement
© 2015 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.
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
Sponsor
Science and Technology Facilities Council (STFC)
The Royal Society
Science and Technology Facilities Council
Grant Number
ST/K001051/1
RP140004
ST/N002776/1
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
RADIO ASTRONOMY OBSERVATIONS
FIELD-ALIGNED CURRENTS
MAGNETIC-FIELD
ROTATION PERIOD
KILOMETRIC RADIATION
MODULATIONS
VOYAGER-2
EMISSION
ORBIT
Publication Status
Published