Dear Authors,

I realise you have done substantial changes to the manuscript in
response to the comments received by the reviewers. Your revised
version has now been seen again by reviewer #3 and you find the
remaining comments by reviewer #3 attached. Reviewer #1 did not
comment on your revised version, despite several attempts from my
side.

In general both reviewers point to the issue of numerical diffusion in
the model. While I realise that you have already done work to address
these comments, I would ask you to pay attention again to this point
when revising your manuscript. Actually, as far as I can see, this
point mainly refers to the employed tracer transport scheme, which is
PPM (and again this point could be more clearly made). Long time ago,
I looked at the issue of numerical diffusion in schemes including PPM
(Müller, R., MWR, 1992, Vol 120., p. 1407); I actually think that you
selected a scheme which really minimises numerical diffusion, which
you might want to emphasise in your manuscript.

Further, reviewer #1 pointed to the issue of the importance of "ice
microphysics". You have now mentioned this point, but my
recommendation is to be more specific; ice microphysics encompasses
many processes. I think specifically in-situ ice nucleation and
subsequent growth of the ice particles is meant here. I suggest to
bring this issue across more clearly.

A final point: the paper should contain a "data availability"
statement according to ACP recommendations.

In summary, I think a few further revisions of your manuscript are
necessary. I apologise for the delay in the review process.

Rolf Müller


Some detailed (editor) comments on your reply :

Rev. #1

Figure A: I suggest you add this figure to the paper as an electronic
supplement, extend the caption somewhat and provide a link to the
supplement in the paper.

page 16, l. 459:

change second line to: "allows the mixture of tropospheric and stratospheric air parcels in the TTL... overshoots to be understood..."

"Sophisticated analyses": provide a bit more detail what sophisticated means here.

page 8, l. 224-228:

"They overshoots"??

page 16., l. 458-459:

"sensitive": can you indicate how the amount changes is the gridspacing is changed (say increased)?

p. 9, l. 253:

"within the overshooting of the..." sentence is unclear

p. 11., l. 301-311:

"shortly" -> "on short time scales"

p. 6., l. 164-167:

"reduced by" --> "reduced to"

p. 14., l. 384-385:

First, "thanks" should be changed to "due to", but the message is
still not clear: why would mixing induce sedimentation? Please
clarify/extend the discussion.

Figure 13:

I am confused: the caption says now that the hatched area in (c) shows
the layer of dehydration. But the hatched area in (c) overlaps with an
area marked as "hydration". Isn't this a contradiction? Please clarify.

p. 16, l 441 remained --> remaining


Rev. #3

p. 13, l 364-365: growth of what?

Fig. 13: see above

p. 6, l. 160-164:

east-northeasterlies: not clear to me

Dear Authors,

thanks very much for your revisions and replies. I am happy to accept your paper for publication in ACP. My only remaining comment is regarding "data availability": perhaps you could indicate the location of the StratoClim data archive (namely the DLR data base) including a web link.

Congratulations,

Rolf