We investigated how to derive subsurface
magnetic structure in an emerging flux region from the
spatial distribution of surface magnetic field observed on the Sun. One such spatial distribution was obtained by Hinode, showing how small magnetic polarity regions (surface magnetic features) evolved to forming a large-scale
bipolar region. By deriving statistical quantities that represent the spatial distribution of these magnetic features and comparing the quantities to those obtained from three-dimensional MHD simulations of flux emergence, we speculated a structural property (field-line twist) of subsurface magnetic field responsible for the spatial distribution of the surface magnetic features.
The subject of this work (how to derive 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