Dear Jiayue Huang et al,

First of all, apologies for my delayed response. I have just returned from a two-month expedition to the high Arctic without internet access.

Thank you for your revised manuscript. The reviewers have read your reply and revised manuscript and only a few (mainly technical) corrections were brought up by reviewer #1. In addition, I have studied your revised manuscript once more in detail and would encourage you to add a few more clarifications to the final manuscript.

In your work, you use the aerosol extinction coefficient as parameter of choice to which model and satellite retrieval are compared to. As you are aware, the ambient extinction coefficient will also depend on the relative humidity due to hygroscopic growth. How are the aerosol optical properties and their hygroscopic growth (e.g. sea spray) parameterized in GEOS-Chem? I think it would be useful to the reader if you add a few lines on this matter to the method section and possibly also to the conclusion and discussion section.

Concerning the CALIOP data: Retrieving extinction coefficients from CALIOP observations requires the assumption of an aerosol-type-specific extinction-to-backscatter lidar ratio, which is another significant source of uncertainty especially for the Arctic region where CALIOP was shown to be generally higher than surface-based in-situ measurements (see Tesche et al., 2014 and references therein). Since this could be another possibility to explain your findings, I would encourage you to add a few more sentence to this aspect to the discussion section.

A few more minor comments:

Figure 6 misses the colorbars in the different panels (a-c and e-h).

Figure 8: Please improve the colorbars for panel c and d (in the later one, the upper and lower boundaries look are not consistent).
Please add correct labels.

Figure S1 & S2: Please add a label to the colorbar.

Please also consider the comments by reviewer #1.

Thanks and kind regards

Paul.

Tesche, M., Zieger, P., Rastak, N., Charlson, R. J., Glantz, P., Tunved, P., and Hansson, H.-C.: Reconciling aerosol light extinction measurements from spaceborne lidar observations and in situ measurements in the Arctic, Atmos. Chem. Phys., 14, 7869-7882, https://doi.org/10.5194/acp-14-7869-2014, 2014.

Dear Jiayue Huang et al.

Thank you for your final revisions. I am pleased to accept your manuscript for final publication in ACP.

Kind regards

Paul.