Cluster Spacecraft Measurements of Dynamic Structures at the Perpendicular Earth's Bow Shock: CIS Observations
Abstract
The Earth's bow shock is the outermost boundary between that region of geospace, which is influenced by Earth's magnetic field and the undisturbed interplanetary medium streaming from the Sun. This boundary is important because it is here that the streaming solar wind is slowed, heated, reflected and partially deflected around the Earth's magnetosphere. As solar wind structures or changes in the solar wind impinge on the bow shock, it moves in response. During the early orbit phase the CLUSTER spacecraft have crossed repeatedly the perpendicular Earth's bow shock and provided the first multi-spacecraft measurements. We have analyzed data from the Cluster Ion Spectrometry experiment (CIS), which observes the 3D-ion distribution function of the major species (H+, He++, He+, O+) in the energy range of 5 eV to 40 keV with 4-second resolution. Beams of reflected ions were observed simultaneously at all spacecraft locations and could be tracked from upstream up to the shock itself. Generally, the spatial evolution across the shock is very similar on all spacecraft, but phased in time. However, occasionally there are differences, e.g. two spacecraft may see identical beam signatures whereas a third spacecraft observes a different beam pattern. Based on these observations we will discuss the dynamic, the geometry and structure of the perpendicular bow shock in space and time.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2001
- Bibcode:
- 2001AGUSM..SM21B06K
- Keywords:
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- 2154 Planetary bow shocks;
- 2164 Solar wind plasma;
- 2194 Instruments and techniques