Two-scale Analysis of Solar Magnetic Helicity
Abstract
The solar magnetic helicity has opposite signs not only in the two hemispheres, but also at large and small length scales. The latter can be detected by computing magnetic helicity spectra, but this must be done separately in each hemisphere. Here we utilize a two-scale method from mean-field dynamo theory that allows us to compute magnetic helicity spectra as a function of two different wavenumbers: one corresponding to rapidly varying scale and one corresponding to a slowly varying one. We generalize this method to spherical harmonics and compute in that way global magnetic helicity spectra for that part of the field that shows a global dipolar symmetry. We present results from simple one-dimensional model calculations, three-dimensional dynamo simulations, and the two-dimensional magnetic field from synaptic vector magnetograms.
- Publication:
-
SDO 2016: Unraveling the Sun's Complexity
- Pub Date:
- October 2016
- Bibcode:
- 2016usc..confE.110B
- Keywords:
-
- SDO;
- SDO 2016;
- Solar Dynamic Observatory;
- SDO-2016;
- SDO Workshop;
- SDO 2016: Unraveling the Sun's Complexity