Comparison between the 4.3 μm CO₂ stretch feature and the 15 μm bending mode in the observations (black) and models with differ- ent vertical photodesorption limits (colored lines). The relative strengths of the features change with the photodesorption threshold due to a dif- ferent spatial origin of the absorption (see Sect. 5.2.1). The shape of the 4.3 μm and especially the red emission wing at 4.30–4.35 μm is also dependent on the height of the photodesorption limit due to geometric effects (see Fig. 9). No detailed fit to ice absorption profiles was per- formed, which could significantly improve the fit at 15 μm (see Bergner et al. 2024, for a fit of the 4.3 μm feature).