The editor would like to thank the authors for their careful consideration of the reviewer comments, lengthy as they were. The subsequent manuscript is now more precise and hence makes a very nice contribution to contrail studies.

I also want to thank the two reviewers for their excellent suggestions and greatly appreciate the time they invested in their reviews.

To the authors,
I have decided to reopen this manuscript for further revision. I offer you my deepest apologies for this inconvenience.

My decision is based on a response I had from one of the reviewers who had selected “I would be willing to review the revised paper, if the Editor considers it necessary”.

I had read your responses to the reviewers and decided that they were sufficient to accept the revision as is. After making this decision and declaring it formally, I sent thank you notes to the reviewers and attached the author responses and revised manuscript.

One of the reviewers responded saying that they were not satisfied with some of the responses and revisions, but given that there had not been a selection that definitively requested to review the revised paper, they chose the only other option, hoping that I would return it to them.

This reviewer also sent me the specific points of concern and I agree that these concerns should be addressed. It was difficult for me as the editor to have recognized these issues yet in retrospect I can understand the reviewer's wishes to have them addressed.

I understand that this process has now extended for a lengthy period, and you were granted several extensions. Please accept my apologies for this additional delay.

I have placed the reviewer comments in the attached file for your consideration. If you will address these with a serious response, I will expedite the publication of this paper as rapidly as possible. From my perspective, the comments should not require a major effort to respond to.

Thank you for your understanding,
Darrel Baumgardner

The authors have made positive progress with the latest revisions and the reviewer has acknowledged this.

There remains one final obstacle that needs to be hurdled before I can accept this paper for publication. The reviewer remains concerned that the issue of ice crystal shattering remains unresolved, as can be seen in the review.

From my perspective, it is my opinion that the reviewer has been clear as to what needs to be done to address this final issue and what is suggested seems very doable in a very short period of time.

Once a revision is ready I will read and discuss with the reviewer, but without going through one more revision if we are both satisfied that the issue has been resolved.

Dear authors,
I deeply appreciate your perseverance and patience through this process of review. In my opinion, it has resulted in a much more concise manuscript and valuable contribution to the volume of information available on contrails and contrail cirrus.

I am accepting this nice paper provisionally as the last reviewer would like you to address a few remaining details (see below).

Cordially
Darrel Baumgardner
Special editor.

-- on page 22 'previous studies' are mentioned several times without a reference.

-- also on page 22 it is stated that 'the polluted cirrus IWC is significantly higher (3.02 mg m -3) than observed in previous studies for clean natural cirrus.' (no reference).

But, comparing mean/median IWC presented here with those reported by Schiller et al. (2008) and Krämer et al. (2016) show a good agreement.

Later in the text a mean IWC of 0.001mg/m3 from previous studies is mentioned for clean cirrus. Where does it comes from? This is definitely at the low end of observed natural cirrus IWC.

-- also page 22: 'The same (sigificantly higher values) holds for ice number concentration with values of 6.66 cm-3 ... . For clean cirrus, typical values of concentration ... are close to 0.1 cm-3 ... (..Voigt et al., 2017). '

The authors compare ice number concentrations in different size ranges! 6.66cm-3 is for sizes larger than 0.4 micron, while 0.1 cm-3 is for sizes larger than 3 micron. Here, the value in parenthesis in Table 3 needs to be compared, which is 0.36/0.214 cm-3 (mean/median), which is in better agreement. The authors mention that later in the text, so the first statement (significantly higher values) needs to be removed.

To the authors,

This review process has been extended over a lengthy period and I sincerely appreciate you perserverance and patience. In the end, I consider that the reviews and subsequent responses and revisions have produced a much improved product that will greatly enhance the data base on contrail cirrus observations.