Dear Maria,

I have looked over the referee comments and your revisions and decided that more work is needed on the manuscript before it is suitable for publication in ACP. Hence the decision of ‘major revisions’. The work required is summarised below. Please contact me if you have any questions on this.

Regards,

Martyn

In his initial review Reviewer 1 had six major points. Of these, I agree that points 1-3 are either not directly relevant to your study or have been largely addressed in the brief way required (but see point 2 below). However, I think you should do more to address his points 4-6 on the other campaign data and errors. On these points your responses (and as far as I can see manuscript changes) were brief. I note that Reviewer 2 was ok with the responses to his/her points.

1. Even if this paper was in preparation at the same time as Navarro et al (2015) it still needs to reflect the current state of knowledge and literature at the time of final revision. You need to respond to Reviewer 1’s comments about the consistency of your study using in-situ data with the remote data presented in other papers, especially NO2. (I agree with you that agreement with other models is not important, but agreement with other data on the campaign is).

2. At present there are only 2 figures in the Supplement. These are the individual profiles are trace gases versus SZA. This was in response to Reviewer’s 1 comment on small scale variability. I think that the information is somewhat hidden in the Supplement and that these 2 figures should be fully integrated into the main manuscript. That will allow you to address the issue of variability in a clearer way.

3. Please also respond to the further comments of Reviewer 1 in his second review.

4. Finally, the paper would benefit from a thorough spelling/grammar check and some wordsmithing by a native English speaker. There are a few of those among the coauthors.