Temperature difference (T(t)−T(0)) cuts. a) Cuts at x = 0 and z = 26.6 Mm (where the maximum temperature is found) between t = 3.2P (thinnest line) and t = 5P (thickest line). The vertical red dashed lines are the borders of the boundary shell, and the red lines are placed at the location of the maximum gradient of the Alfvén speed at each time. b) Staggered cuts along the z direction on the x = 0 at the initial location of the maximum gradient of the Alfvén speed. The green line follows the location of the maximum temperature increase in both plots.