The normal, thickness, and speed of the dusk magnetopause from Cluster Electric Field and Wave experiment measurements
Abstract
We present a measurement of the normal, thickness, and speed of the dusk magnetopause using data from Electric Field and Wave (EFW) experiment at 39 magnetopause encounters by the four Cluster satellites during a single event. EFW measures the potential between spherical probe sensors and the body of the spacecraft. This spacecraft potential is related functionally to the ambient thermal electron current; as such, it gives a primary signature of the magnetopause. We use a timing analysis on the 4 spacecraft data and obtain a system of equations which is solved by regression for the boundary normal vector and speed. This analysis assumes a locally planar magnetopause with its velocity vector colinear with the normal. Magnetopause speeds range from 20 to 200 km/s and current layer thicknesses from 200 to 1200 km. The characteristic time between successive magnetopause encounters suggests a relationship to magnetospheric Pc-5 modes and we discuss the results in the context of an operative Kelvin-Helmholtz instability on the flank magnetopause.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2001
- Bibcode:
- 2001AGUSM..SM61A06B
- Keywords:
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- 2712 Electric fields (2411);
- 2724 Magnetopause;
- cusp;
- and boundary layers