Median averaged profiles of the peak optical depths in radial direction (top) and vertical direction (bottom). The data are displayed in black and models with varying vertical photodesorption threshold in z/r are shown in the colors specified in the colorbar. The dashed gray line shows the fiducial model with a photodesorption limit of A_V = 1.5 mag and the dashed orange line indicates the vertical profile of the CO ice if pure CO ice is considered with a binding energy of 830 K.