We investigated a method for deriving physical properties of subsurface
magnetic field in an emerging flux region from
spatial distributions of surface magnetic field observed on the Sun. One such distribution was obtained by Hinode which captured structure and
evolution of the surface field, showing how small magnetic polarity regions (surface magnetic features) evolved to forming a large-scale
bipolar region. By calculating statistical quantities that represent the spatial distribution of the magnetic features and comparing these quantities to those obtained from three-dimensional MHD simulations for reproducing flux emergence, we derived a structural property (field-line twist) of the subsurface field.
The subject of this work (investigation of a method for deriving physical properties of subsurface magnetic field) was further pursued in this paper.
Reference
Magara, T. 2008 ApJ, 685, L91
Statistical analysis of surface magnetic features in emerging flux region.