Coordinated THEMIS and ground-based magnetometer study of ULF wave excitation during a fast solar wind stream
Abstract
AB: We present results from a study of ULF waves observed during a conjunction between the THEMIS constellation and ground-based magnetometers of the combined CARISMA and THEMIS ground-based observatory (GBO) arrays during a fast solar wind stream in August 2007. Long wavetrain waves in the Pc4 and Pc5 bands were seen across the ground-based arrays during a conjugate overpass of the THEMIS constellation in the dusk magnetosphere over CARISMA on August 8th. The Pc4 waves, also seen on THEMIS, were very monochromatic with many characteristics reminiscent of giant pulsations (Pgs) except that they occurred in the dusk sector. The multiple satellite measurements, including supporting measurements from GOES satellites in this sector, allow characterization of the wavenumbers, spatial scale, and comparison of the widths of the waves on the ground and in space. The monochromatic nature of the Pc4 waves, and their dominant polarization in the D-component on the ground, suggests that they are poloidal Alfven waves perhaps driven by injected ions in the afternoon-side magnetosphere. We use the unique capabilities of the combined THEMIS-GOES constellation, and the extensive ground-based coverage, to address the issue of the source of wave excitation during this high speed stream. Attention is given to internal excitation by energetic ions spectra.
- Publication:
-
37th COSPAR Scientific Assembly
- Pub Date:
- 2008
- Bibcode:
- 2008cosp...37.1903M