Please see supplement.

In this manuscript, the authors evaluate the SW-domain properties of Arctic cirrus clouds as simulated by the IFS model by comparing them with airborne measurements. A similar study was recently published in ACP but for low-level clouds. The subject is important and useful. The work is of very good quality, the results are clear, the analyses relevant and the writing pleasant. This manuscript deserves to be published in ACP and only minor comments and suggestions are made below.

l. 273-274: (comment on Fig. 4) If I understand correctly, the measurements shown between 11 and 11:30 correspond to the results of the simulation at 11:00, and the cloud evolution between 11 and 11:30 is due to the displacement of the aircraft (i.e. the spatial evolution of the clouds) and not to the evolution of the clouds over time. I think this should mentioned more explicitly.

l. 291-292: What do you mean by compensate? The effect of the cosine of the zenith angle?

Figure 8: What is the value of IWC to differentiate between clear and cloudy skies? How are the histograms modified for small values of IWC when this threshold is changed?

l. 318-355 and Figure 9: The value of the IWC has an impact on the radiative flux and it is interesting to show the comparison between the measured values and those of the model. But the flux also depends on the vertical integral of the IWC (i.e. the ice water path, IWP). The IWP depends not only on the IWC but also on the way in which vertical overlaps occur. It would therefore be interesting to compare the IWP as well.

l. 390-391: You talk about the effect of re on the model results, but what is the sensitivity of the estimated values to re? Are the values of re used consistent with those of the model?