Dear authors,

please find enclosed my comments to your manuscript and your responses to the reviewers. I wish you good luck with improving your manuscript and I look forward to receiving a new version which takes into account the issues raised!

With kind regards,

Roeland Van Malderen

Dear authors,

I would like to thank you for taking into account most of the remarks formulated! Unfortunately, using also the MODIS cloud fractions, next to the AIRS cloud fractions, makes the correlations with the biases less clear, which also is true for the discussion in section 4 in particular. When reading the article, you now get the impression that you want to hide some results. Therefore, I would propose to make the following changes:
* when you describe the annual cycle of the AIRS cloud fraction (Fig 6), you should at least mention if the MODIS cloud fraction has a similar annual cycle at the three sites.
* thanks for incorporating Table 4! I would certainly keep it. But a figure says sometimes much more than a Table. Therefore, I would also include the MODIS cloud fractions (and the correlations) in Figs. 7, 8, 10. These are the core figures of the paper: with those, you show the reader visually that the cloud fractions might impact the biases. So, please include the MODIS cloud fraction as well, to show what the impact of the selected cloud fraction dataset is on the cloud fraction - GNSS-satellite bias correlations!
* Fig 9 is not so clear: here you do not see any correlation at all, I would say, and you apparently also have problems to interpret it, because you hardly refer to it in the text. So, you can drop it if you want, but anyway, thanks for constructing the figure.
* For the description in Section 4: it is good to start with the obvious findings (most significant correlations in the same months/seasons for both the cloud cover datasets) and then refine to "more or less" common features in both cloud cover datasets and ending by the clear differences. Now, it is a mixture of different elements and it is clearly guided by your first results (with AIRS cloud cover only), which you try to align/strengthen with the MODIS cloud cover correlations. If you have strong scientific arguments to rely more on the AIRS cloud cover dataset in your discussion, you should mention/explain this in the beginning of the section.
* An obvious question to answer in the conclusions too might be if the GNSS-AIRS biases are stronger correlated to the AIRS cloud covers than to the MODIS cloud covers (and same question for the GNSS-MODIS biases).

Thank you for considering to make those changes and good luck with it!

With kind regards,

Roeland Van Malderen