Representation of the solar wind back-mapping process and its uncertainties assessed in this paper. In the zone of ballistic mapping (above the SS), the lines that connect the spacecraft to the SS represent different trajectories for different velocity profiles of the solar wind; the shaded area around them represents the uncertainty associated with them. The shaded area around the dashed circular line (which shows the SS) represents the uncertainty in its height. In the magnetic mapping zone (below the SS), the magnetic field lines are followed from the SS down to the solar surface (dotted lines). The shaded area around the back-mapped positions on the solar surface represents the uncertainty in the source region of the wind observed at the spacecraft.