Inversion of Ca I 4227 fractional Stokes profiles at µ = 0.07 synthesized in two different vertical columns of a Bifrost model labeled in Guerreiro et al. (2024) as Model A (left panels) and Model D (right panels), in the presence of a height-dependent vertical bulk velocity and magnetic fields. Top panels: fitting of the vertical bulk velocity field to the intensity profile. Left columns: vertical bulk velocity field v_z of the original model (blue dots) and four-nodes fitted (red lines) quantities. Right columns: synthetic input (blue dots) and retrieved (red lines) intensity profiles. Middle and bottom panels: fitting of the magnetic field to the fractional Stokes profiles, exploiting one single node (middle panels) and two nodes (bottom panels). Left columns: magnetic field magnitude, B, inclination, θ_B, and azimuth, χ_B of the original model (blue line) and fitted (red circles) quantities. Right columns: synthetic input I^obs (blue line) and retrieved I^out (red circles) fractional polarization Q/I, U/I, and V/I profiles.