Investigation into the subsurface magnetic structure in an emerging flux region on the sun based on a comparison between hinode's observations and numerical simulations

In this Letter we report a result of investigating the structure of subsurface magnetic field in an emerging flux region on the Sun, which was observed by Hinode. The data obtained by Hinode captured well the structure end evolution of the emerging flux region, showing the appearance of small magnetic features that lead to a welldeveloped bipolar structure. We derived several statistical quantities characterizing the spatial distribution of surface magnetic field. These quantities were then used to investigate the structure of invisible subsurface magnetic field, such as the twist of subsurface field lines, when we compared the observations with numerical simulations performed for the emergence of subsurface magnetic field into the solar atmosphere. The result suggests a possible way of investigating the structure of solar-interior magnetic field by using observational information on solarsurface magnetic field.