Dear authors,

Thank you for submitting your revised manuscript. After reading it together with your response to reviewer comments, and a further review from one of the previous referees, I find that it will be suitable for publication in AMT following a few further minor corrections. These additional comments are:

1. I find Figure 1 in the response letter (intended for the other reviewer) to be useful. Why not include it in the manuscript itself? [Editor note: I leave this up to you, as the Figure could be useful but your current Figures have similar instrument positioning info.]

2. For the Bland-Altman test:
“Besides, we used the metric, which is the percentage of AOD that falls out of the boundary of the mean difference ± 1.96 × the root-mean-squared AOD difference, to indicate the agreement of two measurements.”
Either I’m confused at your description or your intent of this test. Do I understand you’re checking if less than 5 percent of the data fall outside the mean+- 1.96rms, where mean and rms are calculated from the comparison of the datasets? If so, I think this might be a way to check for normality, but it does not illustrate the amount of agreement between the data. If, instead, you are checking how much data fall outside the 0+-1.96U range, where U is calculated as the squared sum of the expected measurement uncertainties of the pair of instruments, then, yes, this is a metric for whether the agreement is good or not. Perhaps I don’t understand, but if that is the case other readers might as well. [Editor note: please check and clarify if needed.]

3. I believe it is SIMBIOS (page 4, line 20)

4. I think some of the grammar, etc. still needs to be cleaned up. The author’s use of the term “Besides” is not correct for what I presume is intended. Depending on the context, this might be replaced by “Additionally” (page 3, 7, 10) “Furthermore” (page 4) or removed (page 6, both cases). [Editor note: the Production Office can handle some of these issues, but I encourage you to check as well, in case the meaning of sentences is affected during Production changes for grammar.]

Please let me know if you have any questions - I do not forsee needing another round of peer-review after attending to the above.

Best wishes,

Andrew

Dear authors,

Thank you for submitting your revised manuscript; I appreciate the response to reviewer comments, and also the extra effort put in to grammatical edits in this version. After reading it through, I am happy to accept this version for publication in AMT. There are a couple of very small textual points which I’d appreciate if you could change when uploading the final files, as I am not sure that typesetting would catch them.

Page 1 line 18: your previous version said “coefficients of determination” but those words were deleted from this version; I think it would be useful to include them for clarity that you’re not talking about regression slope. So I’d write “The linear-regression coefficients of determination between” for the start of this sentence.

Page 1 line 29: “as a function of time of day”.

Page 2 line 27: The acronym PWV was defined in the previous paragraph, so can be used without redefinition here.

Page 3 line 25: One might also state that the offset is well within the calibration uncertainty of these instruments. The 0.002 could be dominated by the funnel contribution or could just be calibration differences.

Page 4 line 26: The acronym SIMBIOS was defined earlier, so can be used without redefinition here.

Page 6 line 25: “system” should read “systematic”.

Please let me know if you have any questions.

Best wishes,

Andrew