Dear Authors,

Three reviewers (all who originally reviewed this manuscript) have now re-reviewed the manuscript. As you will see, there is complete consensus between the 3 reviewers that this manuscript still needs major revision before full publication in ACP can be considered. Due to the nature of these comments, I recommend this manuscript be reconsidered after major revisions. Some of the reviewers are concerned that new errors have now been introduced with the new changes. After my careful review of the revised text and the discussion, I completely agree with all 3 reviewer's concerns. I request that the authors address these reviewer concerns. However, if the authors feel they would not like to revise the manuscript following their comments, I hope these comments will be useful to you in the future if you decide to publish your work elsewhere.

Thank you again for your considering ACP as a venue for publishing your work.

Best wishes, Jason Surratt

Dear Authors, I have now re-reviewed the manuscript as well as the 3 initial reviewers. Their reports are attached here. The first two reviewers think this paper is now ready for publication; however, the third reviewer and I have some remaining revisions that need to be considered before final publication. Based on the nature of the 3rd reviewer's comments and my own final comments, I recommend that this manuscript will be reconsidered after these minor revisions. Once you provide a point-by-point response to these comments, I will assess suitability for publication myself and not seek any further reviewer feedback.

Thanks so much for your revised manuscript, Jason Surratt


Remaining Comments from Reviewer 3:

I suggest that the authors go through the paper, paragraph-by-paragraph, and correct mistakes that bring confusion.

As an example: Even though they have mentioned in their responses that "We have checked and updated the detection limit (0.005 μg mL-1)." the detection limit mentioned in the manuscript is 0.005 mg ml-1...

Overall, I enjoyed reading this paper more this time and the quality has improved but I was hoping for more from the authors.

For instance, the authors should consider identifying the IR bands using the existing literature (e.g. 1040 cm-1, 1195 cm-1; Fig S4 and text).

The relative decays (Fig. S5) don't help much since the initial concentrations varied from 472 to 656 ppb (25-30%!)...The authors should compare the absolute decays and choose experiments when the initial concentrations of cyclohexene are within the same range < 5%.

Page 12, Lines 6-12: To validate this paragraph the authors should plot the sum of the organosulfates (area of the peaks) vs the concentrations of the sulfate measured by IC. Once again the relative contributions do not support what the authors are trying to demonstrate (Fig. S6)

Remaining Comments from the Editor:

1.) Please add text in either the discussion section or the conclusions that further work is needed to quantify the abundance of these organosulfates as well as to determine the precursors to the formation of organosulfates. It is likely these gas-phase precursors formed from cyclohexene oxidation also help to explain the acid-catalyzed enhancements in the SOA mass.

2.) Abstract, Line 19: Please change "first" to "new." Organosulfates being observed is new, but saying first seems like this is the first time ever that organosulfates have been observed in SOA.

3.) Introduction, Page 1, Line 28: change "VOCs oxidation" to "the oxidation of VOCs"

4.) Introduction, Page 2 Line 18: change "area" to "areas"

5.) Introduction, Page 2, Line 21: change "VOCs oxidation" to "oxidation of VOCs"

6.) Introduction, Page 2, Line 25: change "chamber experiments" to "laboratory chamber"

7.) Section Heading 2.3, Page 5: Change "2.3 Products composition analysis" to "2.3 SOA composition analysis"

8.) Section 2.3, Page 5, Line 31: Can you clarify which model of ESI-HR-MS you used and as to whether you mean this was a highi-resolution quadropole time-of-flight mass spectrometer (ESI-HR-QTOFMS)?

9.) Section 3.3., Page 12, Line 8: change "organosulfates yield" to "organosulfate yields"

10.) Section 4, Page 12, Line 19: Change "chamber experiments" to "laboratory chamber"

11.) Section 4, Page 12, Line 19: change "secondary aerosols" to "SOA"

12.) Table 2 and elsewhere: Whenever referring to "m/z" please make sure this is italicized.

13.) Finally, there have been a number of published field studies that have utilized ESI-MS techniques to characterize urban fine aerosols for orgnaosulfates. From Table 2, have the authors carefully reviewed the literature, especially from urban polluted areas where cyclohexene may be important, to see if these products can be detected? Riva et al. (2015, ES&T), Riva et al. (2016, ACP), and studies by the groups of Sergey Nizordov's (UC-Irvine), Alex Laskin's (PNNL and now Purdue University), Marianne Glasius (Aarhus University), and Jian Zhen Yu (Hong Kong University of Science and Technology) have measured many organosulfates in urban areas that are not due to biogenic VOCs like isoprene and monoterpenes.

I'm not saying it is required, but it would certainly add more atmospheric implications to your lab study if you could cite papers that have already been published summarizing organosuflate data from urban areas. I think some of these prior studies may measured organosulfates with unknown sources but with similar chemical formulas as you report in Table 2.

I thank the authors for addressing these final comments. I have now accepted this article for publication in Atmospheric Chemistry & Physics. We hope you'll consider this journal again for your future studies. Most sincerely, Jason Surratt