Network velocity gradients in the photosphere

We present an extension of the Unno-Rachkovsky solution that provides the theoretical profiles coming out of a Milne-Eddington atmosphere imbedded in a magnetic field, and that then takes a vertical velocity gradient into account. Thus, the theoretical profiles may display asymmetries as do the observed profiles, which facilitates the inversion based on the Unno-Rachkovsky theory, and leads to the additional determination of the vertical velocity gradient. We present UNNOFIT inversion on synthetic data and spectropolarimetric observations performed on an active region of the Sun with the French-Italian telescope THEMIS operated by CNRS and CNR on the island of Tenerife.