Dear Dr. Friedrich et al,

Thank you for submitting your response to the reviews. I now have read the original manuscript, reviewer’s comments, your response, and the revised manuscript. While you have responded to most of the comments raised by the reviewers, I feel that some of the responses are not reflected in the revised manuscript. Also, it would be easier to follow your responses had you included the specific modifications you made in the manuscript, i.e. by adding “change in manuscript” in red for each comment from the reviewers. Below I have put some examples.

1) In “Answer to Reviewer 1”, reviewers general comments have been neither responded nor addressed in the manuscript. The reviewer is advising to enhance the analysis and simplify the text by saying
“It certainly is interesting to look at the complete 19 months NO2 data set (e.g. see the discussed averages of the diurnal variation) but my guess is the more interesting studies (specially from an environmental view point) can be done by looking at individual days and using the right ancillary data to understand the NO2 variability and what causes the observed peaks”, and
“However, in some places (e.g. in Section 5, Error analysis) the text can be somewhat difficult to follow, and the manuscript could gain from having another go at streamlining the text a bit more and simplifying the structure of some of the more complicated sentences.”

2) The same reviewer has a comment on clarity by saying “3) Page 2, line 19: ‘(constituting the forward model)’ - What exactly does this mean?” While I am satisfied with your response, this has to be addressed in the manuscript in some way. For instance, you could say “constituting the forward model, VLIDORT”.

3) The same reviewer has a comment to include a brief discussion on errors. I understand that it is done in the QDOAS software, but it would be helpful if you could include a brief discussion on how it is calculated in QDOAS and what is the typical uncertainty in your dSCD. You could of course cite the QDOAS manual for a detailed discussion.

There are too many to list all here, especially for the 2nd reviewer’s comments. Please, read each comment carefully, respond to it (this is usually done except for rare cases), address it in the manuscript if possible (if not, clarify why the suggested change was not made), and include the “changes made in the manuscript” in the author response.

Given the amount of work, I view the effort as a major revision. If you require additional time please let me and the AMT editorial support team know. I look forward to receiving your response and the revised manuscript soon.

Best Regards,

Lok Lamsal
Associate Editor, AMT