Using ACE-Earth Magnetic Connection Events to Estimate Length-scales of Field Line Wandering with respect to the Parker Spiral
Abstract
Whereas the average interplanetary magnetic field near Earth commonly aligns with the Parker spiral in non-transient solar wind, the instantaneous field direction does not, indicating that field lines wander about the spiral direction. The scale-length of that wandering carries information about parallel fluctuations of solar wind turbulence and impacts charged particle transport. Measurement of the scale-length for variations along the mean field direction using single spacecraft measurements is challenging. For this study we used intervals where the ACE spacecraft and Earth's bow shock are magnetically connected to estimate those scale-lengths. We find the local radius of curvature of the interplanetary field is from 5×10-3 to 2×10-2 AU. In addition we estimate that the global length-scale for field line wandering along the Parker spiral is 0.07 ∼ 0.27 AU. That global scale-length roughly agrees with estimations of field-aligned mean-free-path for cosmic ray scattering, as well as braiding lengths associated with granule/supergranule motion on photosphere/corona.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMSH51B2593S
- Keywords:
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- 2164 Solar wind plasma;
- INTERPLANETARY PHYSICSDE: 2169 Solar wind sources;
- INTERPLANETARY PHYSICSDE: 7509 Corona;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7524 Magnetic fields;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY