  Using high-resolution spectropolarimetric data recorded with the Swedish 1 m
Solar Telescope, we have identified several instances of granular lanes
traveling into granules. These are believed to be the observational signature
of underlying tubes of vortical flow with their axis oriented parallel to the
solar surface. Associated with these horizontal vortex tubes, we detect in some
cases a significant signal in linear polarization, located at the trailing dark
edge of the granular lane. The linear polarization appears at a later stage of
the granular lane development, and is flanked by patches of circular
polarization. Stokes inversions show that the elongated patch of linear
polarization signal arises from the horizontal magnetic field aligned with the
granular lane. We analyze snapshots of a magnetohydrodynamic numerical
simulation and find cases in which the horizontal vortex tube of the granular
lane redistributes and transports the magnetic field to the solar surface
causing a polarimetric signature similar to what is observed. We thus witness a
mechanism capable of transporting magnetic flux to the solar surface within
granules. This mechanism is probably an important component of the small-scale
dynamo supposedly acting at the solar surface and generating the quiet-Sun
magnetic field.
