No abstract

[1] We have examined four well-defined events of sawtooth oscillations in energetic particle flux and magnetic field at geosynchronous orbit. During all four events, nearly simultaneous energetic particle flux enhancements and magnetic field variations occurred at all MLTs for each sawtooth cycle. Geomagnetic H component data at low to middle latitude also show a global H increase simultaneously with the geosynchronous responses at all MLTs, and the northern and southern PC indices generally show increases at each sawtooth cycle. All these are what is expected if solar wind pressure enhancements impacted the magnetosphere at times appropriate to have caused the onset of each sawtooth cycle. By directly checking the solar wind data, we find that there indeed exists a series of solar wind dynamic pressure enhancements for each sawtooth event. In identifying these pressure enhancements, we have found that the relative change in the dynamic pressure is important, particularly when the magnitude of the dynamic pressure is small and that even a modest dynamic pressure enhancement can result in significant changes in the magnetosphere when the IMF stays strongly southward for a long interval. We show that each cycle of the sawtooth oscillation can be reasonably associated in timing with a corresponding solar wind dynamic pressure enhancement. On the basis of this association and the global, simultaneous geosynchronous and ground responses, we suggest that the sawtooth oscillations studied in this paper are directly driven by series of solar wind pressure enhancements and are not a repetitive internal magnetospheric response to sustained enhanced solar wind energy input.

We present a study of the response of the geosynchronous magnetic field to abrupt enhancements of the solar wind dynamic pressure. Results are obtained separately for cases of northward and southward interplanetary magnetic field (IMF) prior to and after the solar wind pressure jump. For pressure enhancements with southward IMF we find that the response of the geosynchronous magnetic field on the dayside is mostly compression. However, on the nightside it can be a dipolarization‐like change that is similar to that which occurs during substorms. We report four events showing the dipolarization‐like response on the nightside. Analysis using low‐latitude geomagnetic data as well as the geosynchronous energetic particle flux data leads us to argue that this dipolarization is part of the global disturbance directly driven by the solar wind pressure enhancement. We also find that the nightside magnetosphere is remarkably sensitive to small solar wind dynamic pressure enhancements when the IMF is strongly southward (i.e., Bz is below ∼−10 nT). For northward IMF, solar wind pressure enhancements generally lead to magnetic compression, with a few cases of depression on the nightside, neither of which is a dipolarization‐like response. The compression is strongest near noon, decreases toward dawn and dusk, and increases with the amount of increase in dynamic pressure.

The anatomic variations of the intrathoracic nerve of Kuntz and the second thoracic sympathetic ganglion were characterized in human cadavers. It is hoped that this study will help to improve the recurrence of symptoms caused by the intrathoracic nerve in an upper thoracic sympathectomy for hyperhidrosis.