Evolution and characteristics of global Pc5 ULF waves during a high solar wind speed interval
Publication date: 15 December 2005
Authors: Rae, I.J. et al.
Journal: Journal of Geophysical Research
Volume: 110
Issue: A12
Page: A12211
Year: 2005
Copyright: American Geophysical Union
We present an interval of extremely long-lasting narrow-band Pc5 pulsations during the recovery phase of a large geomagnetic storm. These pulsations occurred continuously for many hours and were observed throughout the magnetosphere and in the dusk-sector ionosphere. The subject of this paper is the favorable radial alignment of the Cluster, Polar, and geosynchronous satellites in the dusk sector during a 3-hour subset of this interval that allows extensive analysis of the global nature of the pulsations and the tracing of their energy transfer from the solar wind to the ground. Virtually monochromatic large-amplitude pulsations were observed by the CANOPUS magnetometer chain at dusk for several hours, during which the Cluster spacecraft constellation traversed the dusk magnetopause. The solar wind conditions were very steady, the solar wind speed was fast, and time series analysis of the solar wind dynamic pressure shows no significant power concentrated in the Pc5 band. The pulsations are observed in both geosynchronous electron and magnetic field data over a wide range of local times while Cluster is in the vicinity of the magnetopause providing clear evidence of boundary oscillations with the same periodicity as the ground and geosynchronous pulsations. Furthermore, the Polar spacecraft crossed the equatorial dusk magnetosphere outside of geosynchronous orbit (L ~ 6-9) and observed significant electric and magnetic perturbations around the same quasi-stable central frequency (1.4-1.6 mHz). The Poynting vector observed by the Polar spacecraft associated with these pulsations has strong field-aligned oscillations, as expected for standing Alfvén waves, as well as a nonzero azimuthal component, indicating a downtail component to the energy propagation. - Remainder of abstract truncated -
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