Magnetic fields are usually observed in the quiet Sun as small-scale elements
that cover the entire solar surface (the `salt and pepper' patterns in
line-of-sight magnetograms). By using 3D radiative MHD numerical simulations we
find that these fields result from a local dynamo action in the top layers of
the convection zone, where extremely weak 'seed' magnetic fields (e.g., from a
10−6 G) can locally grow above the mean equipartition field, to a stronger
than 2000~G field localized in magnetic structures. Our results reveal that the
magnetic flux is predominantly generated in regions of small-scale helical
downflows. We find that the local dynamo action takes place mostly in a
shallow, about 500~km deep, subsurface layer, from which the generated field is
transported into the deeper layers by convective downdrafts. We demonstrate
that the observed dominance of vertical magnetic fields at the photosphere and
horizontal fields above the photosphere can be explained by small-scale
magnetic loops produced by the dynamo. Such small-scale loops play an important
role in the structure and dynamics of the solar atmosphere and that their
detection in observations is critical for understanding the local dynamo action
on the Sun.Comment: 40pages, 18 figures; accepted to ApJ. arXiv admin note: text overlap
with arXiv:1312.098
