Details

Autor(en) / Beteiligte

• El‐Alaoui, Mostafa
• Richard, Robert L.
• Nishimura, Yukitoshi
• Walker, Raymond J.

Titel

Forces driving fast flow channels, dipolarizations, and turbulence in the magnetotail

Ist Teil von

• Journal of geophysical research. Space physics, 2016-11, Vol.121 (11), p.11,063-11,076

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2016

Quelle

Wiley Online Library

Beschreibungen/Notizen

• Fast flow channels are a major contributor to earthward transport in the magnetotail. Fast flow channels originate at reconnection sites in the magnetotail and terminate with dipolarizations, earthward moving regions of enhanced magnetic field. We have used a global magnetohydrodynamic simulation of magnetotail dynamics during a substorm on 7 February 2009 to investigate the stresses in the plasma sheet. In particular, we present an analysis of forces in and around flow channels and dipolarizations. Earthward of the dipolarization magnetic and thermal pressure forces are nearly in equilibrium. Tailward of the dipolarization the pattern of stresses is complex, but several general features are evident. In the earthward flow channel the magnetic tension force dominates. In the dipolarization a tailward magnetic force is partially balanced by the earthward pressure force. The stresses in azimuth (y) are variable. In some places they cause the flow stream to meander, while in others they cause the stream to become wider or narrower. A major consequence of fast earthward flow channels is that they drive large‐scale vortices that initiate turbulence. Key Points Starting from a broad reconnection region flows and dipolarizations propagate earthward and are constrained in azimuth by pressure forces We found that the development of flow channels and dipolarizations coincided with increases in turbulent power In the flow channel, tailward of the dipolarization, the earthward magnetic tension force dominates