Abstract
Electric currents in solar active regions are thought to provide the energy released via magnetic reconnection in solar flares. Vertical electric current densities J z at the photosphere may be estimated from vector magnetogram data, subject to substantial uncertainties. The values provide boundary conditions for nonlinear force-free modelling of active region magnetic fields. A method is presented for estimating values of J z taking into account uncertainties in vector magnetogram field values, and minimising \(J_{z}^{2}\) across the active region. The method is demonstrated using the boundary values of the field for a force-free twisted bipole, with the addition of noise at randomly chosen locations.
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The author thanks the referee, Thomas Wiegelmann, for comments that helped improve this paper.
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Wheatland, M.S. Estimating Electric Current Densities in Solar Active Regions. Sol Phys 290, 1147–1157 (2015). https://doi.org/10.1007/s11207-015-0672-5
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DOI: https://doi.org/10.1007/s11207-015-0672-5