On potential field models of the solar corona

摘要: The current-free approximation has been widely used to infer the magnetic structure of solar corona from magnetograph observations. In such calculations, potential field is usually matched directly observed line-of-sight component photospheric field. However, this procedure invalid because measurements apply deep atmospheric layers where nonpotential and (for observations made in Fe I λ5250 line) nearly radial. A better approach match only radial data (corrected for projection on assumption that lines are radially oriented), while allowing a discontinuity tangential components