Evolution of the maximum horizontal velocity of the flow within the spot boundary (blue), its surrounding region (grey), and the horizontal velocity at the spot boundary (red) for three selected active regions for Case (i) and five active regions for Case (ii). The loss of the penumbra was set as a common point in time, i.e., t = 0 h. Black symbols and short vertical lines indicate the crossing of the meridian of the respective AR within the evolution.