Magnetic Island Formation Between Large-Scale Flow Vortices at an Undulating Post- noon Magnetopause for Northward IMF
Abstract
THEMIS multi-spacecraft observations are presented for a ~2 hour-long post-noon magnetopause event on 8 June 2007 that for the first time indicate that the trailing (sunward) edges of Kelvin-Helmholtz (KH) waves are commonly related to small-scale <0.5 RE magnetic islands or flux transfer events (FTE) during the growth phase of these surface waves. The FTEs typically show a characteristic bipolar BN structure with enhanced total pressure at their center. Most of the small-scale FTEs are not related to any major plasma acceleration. TH-A observations of one small FTE at a transition from the low-latitude boundary layer (LLBL) into a magnetosheath plasma depletion layer were reconstructed using two separate techniques that together confirm the presence of a magnetic island within the LLBL adjacent to the magnetopause. The island was associated with a small plasma vortex and both features appeared between two large-scale (~1 RE long and 2000 km wide) plasma vortices. We propose that the island may have been generated from a time-varying reconnection process at the sunward edge of the growing KH waves where the local magnetopause current sheet could be compressed by the action of the large-scale plasma vortices as suggested by numerical simulations of the KH instability.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMSM53B..08E
- Keywords:
-
- 2723 Magnetic reconnection (7526;
- 7835);
- 2724 Magnetopause and boundary layers;
- 2752 MHD waves and instabilities (2149;
- 6050;
- 7836)