Reviewer #2 said that the paper suffers from analyzing a small region over a few days, making it hard to draw broader conclusions. Reviewer #2 further said that the paper should either 1) make clear how the paper is methdologically novel or 2) analyze a longer period(s) so that we understand better how general the results are. I understand that the focus is on severely polluted conditions, and so you wouldn't simulate a full year, for example.

I agree with Reviewer #2's assessment. In response, no case is made for methodological novelty. Two additional short episodes are added to the paper, for which apparently similar conclusions are reached. But those two episodes are added as an after-thought - they appear only in a separate Discussion section, with all relevant figures in the supporting information. No case is made for why these two extra episodes are less important to justify keeping the focus on the first episode.

I do not think it would be worthwhile to send the current version to the same referees in its current form. Rather, I think the authors should rewrite the paper to talk about the analysis of 3 episodes throughout, from the introduction through to conclusions - unless the authors can justify the main focus on one episode and secondary focus on the 2 others. You are free to respond as you'd like, but that is my strong recommendation.

Apart from that, I felt that the authors gave good responses to many of the individual points from the 2 referees, but often did not go far enough to change the paper itself to address those concerns. For example, Figure R2 seems to me to show that the model is a factor of two too low in AOD.

If you would like to resubmit to ACP, please make substantial revisions to the paper to incorporate the 3 episodes throughout the paper, and prepare an improved response to reviewers that more fully shows how the paper is improved as a results of responding to comments.

Please respond to the comments of the reviewer. In particular, it seems that the paper is still not communicating clearly why these 3 high pollution episodes are relevant or important to study, and consequently,how to interpret the conclusions to make broader inferences about other time periods.

To me, analyzing 3 short episodes in one location is only sufficient for a paper in ACP if the authors motivate well why those episodes are important to study, putting them in a broader context.

The last draft was marked "major revision" but it appears to me that no major revision was made. In fact, no changes were made at all to the Introduction and Methods sections. The major comment from the reviewer, which I reiterated, was that the paper does not sufficiently motivate the focus on 3 episodes, nor discuss the relevance of the results for other periods of time. The paper still does not state why these 3 episodes were chosen. The paper also seems to be motivated to study high pollution conditions, but that is not stated in the major objectives. And while the authors responded to my comments and the reviewer's first comment, no changes were made in the paper itself to clarify these points.

What is the goal of the paper - to consider high air pollution conditions, and for what purpose?

Why were the three episodes chosen, and what do we hope to learn more generally for other conditions?

How do the conclusions based on the three episodes relate with other conditions during the years studied (2014-16) and to what extent are they relevant for other years before or after?

I decided to reject this paper for two main reasons.

1) The relevance of this study for other episodes within this period studied and since 2017 is not entirely clear, though I appreciate you've made some efforts to address this question.

2) It is very unusual to have new simulations presented in the final paragraph of the paper.

I'm sure you're disappointed with this decision, but with the improvements you've made, I'm hopeful that this can be published in another journal - as long as you make clear the goals of the study and the relevance of the episodes studied for conditions seen more generally.

The reviewer makes some constructive suggestions which are generally in line with my earlier comments. The paper has improved from the earliest submissions, and I think that it can still improve with attention to these comments.