J. Space Weather Space Clim.
Volume 2, 2012
|Number of page(s)||7|
|Published online||02 August 2012|
Magnetic twist: a source and property of space weather
Nordita, AlbaNova University Center, Roslagstullsbacken 23, SE-10691 Stockholm, Sweden
2 Department of Astronomy, AlbaNova University Center, Stockholm University, SE-10691 Stockholm, Sweden
* corresponding author: e-mail: firstname.lastname@example.org
Accepted: 10 July 2012
Aim: We present evidence for finite magnetic helicity density in the heliosphere and numerical models thereof, and relate it to the magnetic field properties of the dynamo in the solar convection zone.
Methods: We use simulations and solar wind data to compute magnetic helicity either directly from the simulations or indirectly using time series of the skew-symmetric components of the magnetic correlation tensor.
Results: We find that the solar dynamo produces negative magnetic helicity at small scales and positive at large scales. However, in the heliosphere these properties are reversed and the magnetic helicity is now positive at small scales and negative at large scales. We explain this by the fact that a negative diffusive magnetic helicity flux corresponds to a positive gradient of magnetic helicity, which leads to a change of sign from negative to positive values at some radius in the northern hemisphere.
Key words: MHD / turbulence / solar activity / coronal mass ejection (CME) / solar wind
© Owned by the authors, Published by EDP Sciences 2012
This is an Open Access article distributed under the terms of creative Commons Attribution-Noncommercial License 3.0
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