Analysis of Electric Current Helicity in Active Regions on the Basis of Vector Magnetograms
Abstract
The problem of (dc) magnetic field energy build up in the solar atmosphere is addressed. Although large-scale current generation may be due to large-scale shearing motions in the photosphere, recently a new approach was proposed: under the assumption that the magnetic field evolves through a sequence of force-free states, Seehafer (1994) found that the energy of small-scale fluctuations may be transferred into energy of large-scale currents in an AR (the α-effect). The necessary condition for the α-effect is revealed by the presence of a predominant sign of current helicity over the volume under consideration. We studied how frequently such a condition may occur in ARs.
- Publication:
-
Solar Physics
- Pub Date:
- September 1996
- DOI:
- 10.1007/BF00145826
- Bibcode:
- 1996SoPh..168...75A
- Keywords:
-
- Magnetic Field;
- Active Region;
- Solar Atmosphere;
- Field Energy;
- Vector Magnetic Field