Rotational velocity of MHD disk wind. The figure shows an example of the rotational velocity in the jet (v_ϕ); the direction of this velocity is into the page. Up to the Alfvén surface (green line), the magnetic field almost enforces isorotation to the plasma despite the opening of the flow. The decrease of the rotation velocity occurs only beyond the Alfvén surface. The wind values for this plot are the same as in Fig. 5.