  We have examined the spatial and polarimetric properties of these events
using a variety of data from the Hinode spacecraft. We have also inferred the
atmospheric stratification of the physical parameters by means of the inversion
of the observed Stokes profiles employing the Stokes Inversion based on
Response functions (SIR) code. Finally, we analyzed their evolution using a
time series from the same instrument. Blue-shifted events tend to appear over
bright regions at the edge of granules, while red-shifted events are seen
predominantly over dark regions on intergranular lanes. Large linear
polarization signals can be seen in the region that connects them. The magnetic
structure inferred from the time series revealed that the structure corresponds
to a $\Omega$-loop, with one footpoint always over the edge of a granule and
the other inside an intergranular lane. The physical parameters obtained from
the inversions of the observed Stokes profiles in both events show an increase
with respect to the Harvard-Smithonian reference atmosphere in the temperature
at $\log\tau_{500} \in (-1, -3)$ and a strong magnetic field, $B \ge 1$ kG, at
the bottom of the atmosphere that quickly decreases upward until vanishing at
$\log\tau_{500} \approx -2$. In the blue-shifted events, the line of sight
velocities change from upflows at the bottom to downflows at the top of the
atmosphere. Red-shifted events display the opposite velocity stratification.
The change of sign in line of sight velocity happens at the same optical depth
in which the magnetic field becomes zero. The physical mechanism that best
explains the inferred magnetic field configuration and flow motions is a siphon
flow along an arched magnetic flux tube. Further investigation is required
however, as the expected features of a siphon flow cannot be unequivocally
identified.
