  The complex dynamics that lead to the emergence of active regions on the sun
are poorly understood. One possibility is that magnetic structures (flux tubes,
etc.) rise from below the surface by self induction and convection that lead to
the formation of active regions and sunspots on the solar surface. For space
weather forecasting, one would like to detect the subsurface structures before
they reach the surface. The goal of this study is to investigate whether sound
speed perturbations associated with subsurface structures could affect the
acoustic power observed at the solar surface above them. Possible mechanisms
for this effect are wave reflection, scattering or diffraction.
  By using numerical simulations of wave propagation in the solar interior, we
investigate whether observations of the acoustic power can be used to detect
emerging active regions before they appear on the surface. In the simulations,
subsurface structures are modeled as regions with enhanced or reduced acoustic
wavespeed. We show how the acoustic power above a subsurface region depends on
the sign, depth and strength of the wavespeed perturbation. For comparison, we
analyze observations from SOHO/MDI of the emergence of solar active region NOAA
10488.
