Dear Dr. Daniel Murphy,

I received the review report for the revised version of your manuscript form Referee #2, who still thinks that the manuscript needs further major revision.

I also got the following comments on your revised manuscript from Referee #1, who recommends rejection of your manuscript:
“I have had the opportunity to read the revised manuscript and response to reviewers. While the authors have made many technical revisions, they have not addressed the fundamental issue brought up in the reviews - that the discussion (primarily sections 6 and 7) is highly speculative and well outside the scope of the analysis in the prior sections. I do not see a path to resolving this issue without the final manuscript being an entirely different manuscript from what was submitted both in structure and scope. This is not something that I feel will be resolved with a further review. Therefore, I must respectfully decline to provide further review and maintain my prior recommendation”.

Please consider the comments from both referees carefully and make revisions further as they suggested and/or give necessary responses.

Sincerely,
Jianzhong Ma

Dear Dr. Daniel Murphy,

According to the referee comments and also in my point of view, your manuscript still needs minor revision before acceptance for publication in ACP. I am concerned with the content of ‘Section 6 Relevance to volcanic or intentional aerosol injection’, which seems not to have a strong linkage with (or supported by) measurement results presented in previous sections. I would suggest that Section 6 be skipped over or reduced and then merged into Section 7. Below are specific comments, some of which are technic.

L24: The expression ‘the surfaces used’ is not so clear. Do you mean ‘the substances used’?

L31: over 60 years since 1961?

L59-60: Do you mean most “single” particles larger than about 110 nm? Are these particles internally mixed, e.g., containing an organic core coated by sulfate or vice versa?

L89-97: While the UHSA and LAS recorded the data at 1s intervals, how about the sampling frequency of PALMS for particle composition?

L138-139: What radiative transfer model was used? Better to provide some information here, instead only referring to Murphy (2009).

L208-209: It is difficult to follow the discussion here. How are the tropospheric mode and stratospheric particles defined? Please describe the method or threshold used to distinguish the modes (aerosols) between the stratosphere and troposphere here and/or in the caption of Figure 2. If applicable, the same legends can be used in Figure 2 as in Figure 1.

L244: The phrase ‘were both local springtime’ can be changed to ‘were observed both in local springtime’.

L255: Since ammonium sulfate aerosol has very low volatility, it might not be so meaningful to discuss the equilibrium of ammonia with it. Did you find ammonium nitrate by the PALMS? Otherwise, I would suggest that ammonia be omitted.

L268-269: Does the CESA/CARMA model include these species and associated gas-particle processes? If applicable, what specific species used in the model?

L374: Change ‘than in the stratosphere than’ to ‘in the stratosphere than’.

L486-509: It is difficult to follow the discussions in these two paragraphs. While it is declared at the beginning (L488) that infrared absorption is almost independent of size, the infrared effect (L490), relative infrared effect (L492) and infrared absorption (L496) are said to be size dependent. I could not see the infrared effect on net cooling as a function of size from Figure 7 as stated in L489-490, neither high sedimentation rate (downward triangles) in Figure 9. The ‘IR heating’ appearing in the legend of Figure 9 is unclear.

L547-549: This paragraph seems to be repeating the discussion given in previous section.

Figures 7 and 9: The model and input parameters used to derive these two plots are not well described. What data from the ATom mission are used for the calculation?

Sincerely,
Jianzhong Ma

Dear Dr. Daniel Murphy,
Thanks to the reviewers’ comments and your efforts, the manuscript has improved greatly. I am happy to see it moving to ACP.
Sincerely,
Jianzhong Ma