Peer review of: Electron Bernstein waves driven by electron crescents near the electron diffusion region (2020)


RR2

Reviewers' comments:
Reviewer #1 (Remarks to the Author):
The authors should acknowledge in the paper, near line 182, that there is a discrepancy between their simulations and observations regarding where the wave powers peak between the harmonics, if they like including their speculation about the reason for it. A sentence is sufficient, but it shouldn't go unacknowledged, as it is too obvious a feature.
Aside from this minor comment, paper is much improved as to clarity of presentation and is suitable and appropriate for publication.
Reviewer #2 (Remarks to the Author):
The reply addressed all my comments, thus I support to publish this paper.
Reviewer #1 additional comments during consultation (Remarks to the Author):
I think one of the main problems with this paper is that it's way too terse. I assume that the authors are working against a fairly severe page/figure number limitation? I think clarity and reproducibility of the study suffer because of the extreme terseness.
On my comments, I was a little disappointed to see in the rebuttal, for example, that they claim in two places that "filtering information...is added in the captions and the figures," when, as far as I can tell, the information is added in the figures only. This is annoying because it suggests the rebuttal can't really be trusted, every little thing has to be checked.

The other two things on my comments: it's nice to see Figure R2 and accompanying discussion in the rebuttal, but at the very least the criterion E_\perp > E_max/e^2 should be in the text, not just in the communication to the referee. The idea here is, to try to document things so that someone has a chance of reproducing the result.
Finally, in the rebuttal the authors admit my point that the data, in contrast to their theory, show peaks between rather than at gyroharmonics, and they suggest a reason for the discrepancy and a future study to clarify it, but none of this makes it into the paper. I think it should, because my observation is rather obvious and will occur to other readers.
On to referee 3---Referee 3 is a lot more critical of the paper than I am.
His/her principal issue is whether the authors overstepped in implying that the EBW's are an agent of causing the reconnection versus the agyrotropicity (which is purported to also cause the EBWs) being the main cause. The referee wants this subject explored more, and the authors basically argue that it requires difficult simulations beyond the scope of the paper. None of their argumentation makes it into the paper. I don't have access to the previous version to see what the original statement was in the abstract, but it does appear the authors may have toned down their conclusions, perhaps sufficiently to satisfy referee 3. They say that the EBW contribute to the cross field diffusion but don't suggest they are the predominant factor. I suspect referee 3 would like to see some of the discussion in the rebuttal, concerning the competing effects and the need for detailed PIC simulation to sort it out, make it into the paper rather than just in the rebuttal to the referee. Adding some of this discussion would address referee 3s biggest concern that the paper kind of implicitly suggests a larger role for the waves than it really proves.
Another issue raised by referee 3 is need for a more details of how the initial conditions for the instability calculation were determined.
Again, the authors provide a lot of information in the rebuttal (Fig R6 and second paragraph above it), none of which makes it into the paper. I would concur with referee 3 in wanting to see some of this in the paper---again, so that readers have a fighting chance of reproducing the work.
Referee 3 also brings up some technical matters about aliassing of electron distribution measurements and terminologies and determinations of directions related to 3D distributions. I guess I feel the authors have probably sufficiently addressed these points in the rebuttal. Additional wording in the paper could help clarify these things.
Upshot is: I feel the authors should include somewhat more in the paper.

Does this journal allow submission of auxiliary materials? That could be a solution if strict page or line number limits prevent lengthening of the paper. If the authors are not up against such strict page or line number limits, they really should expand a little bit to make the paper clearer.