Cuts through the divergence (top row), x component of the velocity (bottom left), and y component of the velocity (bottom right). The red lines show these quantities for averaging over ARs at t = −13.6 h (as in Fig. 4), and the black lines show the corresponding quantities as predicted by the model described in this section. In all panels the divergence or velocity has been averaged in a strip of width 11.1 Mm perpendicular to direction of the cut. The model is a reasonable qualitative explanation of the divergence and y component of velocity. For both the observations and the model, the x component of the flow is weaker than the y component.