Dear authors,

Firstly, I'd like to thank the two reviewers for taking the time to review the submitted
manuscript. Their reviews were very positive and in favour of publication in Geoscientific
Model Development. I'd also like to thank you again for your patience in relation to the
original delay due to the ACP companion paper and for submitting a revised manuscript.

In the case of the 1st reviewer, some of their minor comments were not formatted very
clearly and below I make some suggestions about the interpretation of their comments.
Other than that, I will happily recommend that your paper be accepted for publication
in GMD.

What great reviews! Well done on a very well written and clear paper,
Fiona O'Connor


1. Abstract: I have no problem with the statement "climate models oftern use
...". However, I would replace "So far" with "To date".

2. Abstract: Replace "single processes" with "individual processes". The word "single"
really suggests that there is only one process whereas individual does refer to
a single process but there can be a number of them. Hope that makes sense.

3. Abstract: line 11: I think the reviewer is asking that you remove some of the
dupliation in this sentence. And again, the duplication is related to the
expression "single process" - see also comment above.

4. Abstract: 15/16: Not sure what the reviewer is requesting here. As it stands,
this seems okay albeit a bit lengthy. You could shorten it slightly by
replacing the "the rates of change in the original Polar SWIFT version" with
"in the original Polar SWIFT model, they included ...."

5. Abstract: line 20 - I would prefer if you said "observations and output from
the original detailed chemistry model, ATLAS"

6. Abstract: Page 2, (New) line 30:
How about splitting the sentence "In contrast to other fast ozone schemes for
climate models like the Cariolle scheme (Cariolle and Déqué, 1986; Cariolle
and Teyssèdre, 2007) or Linoz (McLinden et al., 2000; Hsu and Prather, 2009),
which were originally designed to model only extrapolar ozone, the SWIFT model
is not based on a single linear differential equation based on a Taylor series expansion,
but on a set of coupled non-linear differential equations representing the main processes
changing polar ozone." to

"Other fast ozone schemes developed for climate models, like the Cariolle scheme
(Cariolle and Déqué, 1986; Cariolle
and Teyssèdre, 2007) or Linoz (McLinden et al., 2000; Hsu and Prather, 2009),
were originally designed to model only extrapolar ozone. In contrast, the SWIFT model
is not based on a single linear differential equation based on a Taylor series expansion,
but on a set of coupled non-linear differential equations representing the main processes
changing polar ozone."

7. Abstract: Page 3, (New) line 3: The reviewer, I think, wanted you to include the expression
"more realistically" when discussing climate change so, I would suggest the following:
"The Polar SWIFT model is therefore able to represent ozone-climate interactions during
climate change (in combination with the Extrapolar SWIFT model) more realistically."

8. Importance of FAP and FAPs: You mention that "The decision to use FAP or FAPs is based
empirically on the quality of the fit for the single equations. A special case is the
denitrification, which is based on sedimenting NAT particles in the ATLAS model and is
parameterized with FAPs." I guess the reviewer is asking you to be a bit more specific
about the regions and time periods when you parameterize with FAPs. Can you expand on
this a bit more?