We obtain information about the magnetic flux present in the quiet Sun by
comparing radiative MHD simulations with Hinode/SP observations, with
particular emphasis on the role of surface dynamo action. Simulation runs with
different magnetic Reynolds numbers (Rm) are used together with observations at
different heliocentric angles with different levels of noise. The results show
that simulations with an imposed mixed-polarity field and Rm below the
threshold for dynamo action reproduce the observed vertical flux density, but
do not display a sufficiently high horizontal flux density. Surface dynamo
simulations at the highest Rm feasible at the moment yield a ratio of the
horizontal and vertical flux density consistent with observational results, but
the overall amplitudes are too low. Based on the properties of the local dynamo
simulations, a tentative scaling of the magnetic field strength by a factor 2 -
3 reproduces the signal observed in the internetwork regions. We find an
agreement with observations at different heliocentric angles. The mean field
strength in internetwork, implied by our analysis, is roughly 170 G at the
optical depth unity. Our study shows that surface dynamo could be responsible
for most of the magnetic flux in the quiet Sun outside the network given that
the extrapolation to higher Rm is valid.Comment: accepted in A&