Well written paper showing vegetation feedback of fire-enhanced O3 based on modelling approaches.  The results are supported by showing O3 vegetation feedback with and without fire. I would recomend to slightly change the Introduction so that the reader would be able to follow the text more fluently and the paragraphs will follow each other more logically.

Here are some more detailed comments:

line 23: fire is not a source of ozone. Please rewrite it in a manner that it produces precursors of O3. Moreover the sentence has double meaning - it is a fire and O3, which causes damage to vegetation and reduces stomatal conductance.

line 70-71: here you write the same as in line 49-50

line 79: cite the three papers here

line 88-90:when the O3 is enhanced, one would expect higher deposition velocity. Could you explain why in that case it is the opposite?

line 103-105: how do the influence the sources and sinks? I think it influence more sinks. Now it seems as the reduces LAI would be a source of O3, when it is just reducing sink of O3. Moreover, there is a new review about O3 effect on vegetation, which you might consider to include here. 10.3390/atmos12010082

line 203-204: is that true? One would expect oxidation of the compounds and sedimentation of particles  before reaching BL

 line 256-258: is the mean annual or is the mean from 2005-2012, which is longer time that annual.

line 381: I think you just hypothesize, that it is due to reduced stomatal conductance. There is no model feedback showing this nor your measurement.

Fig 6: explain abbreviations AMZ, CAF, SAS as in Fig. 3

This paper examines the effects of fires on surface ozone pollution and the subsequent feedback effects that may further enhance ozone. This runs along the excellent of work this group of researchers have done demonstrating the importance of ozone-vegetation interactions in atmospheric chemistry modeling and air quality projections. While the idea of ozone-vegetation feedbacks is not new by now, this paper presents a new perspective by focusing on fires, which distinguishes itself from previous ozone-vegetation papers that focused on anthropogenic emissions. There are however several aspects which I believe need to to be addressed, and revisions need to be made, before this paper can be published. Please see below for my comments and suggestions.

P4 L68-74:

First of all, it should be “vegetation damage” that would influence the sources and sinks of ozone via various “feedbacks”. Second, the authors mentioned the distinction between “biogeochemical” and “biogeophysical” feedbacks, but it needs to be explained further. What are the distinctions? In particular, in the following few sentences, only “biogeochemical” processes are considered, but the “biogeophysical” pathways are not mentioned at all.

In general, the whole introduction lacks a thorough illustration of the detailed feedback pathways and the distinctions between the biogeochemical and biogeophysical effects of vegetation on air quality (and thus feedbacks after ozone damage). I suggest having a separate paragraph detailing first how vegetation processes affect ozone air quality, distinguishing between the biogeochemical (i.e., BVOC emissions and dry deposition) and biogeophysical (i.e., transpiration and the subsequent changes in meteorological environment) pathways. A paper that can be referenced on these is Wang et al. (2020). After such an introduction, the feedback effects can be explained much more clearly.

P5 L89-90:

In Sadiq et al. (2017), much of the positive feedback is due to “biogeophysical” effects, i.e., reduced transpiration leading to higher surface temperature and thus higher isoprene emissions, then higher ozone. Reduced dry deposition velocity is roughly only half of explanation. In general, in this whole paragraph, the distinctions in methodology or pathways included should be explained more clearly. E.g., Zhou et al. (2018) and Gong et al. (2020) only considered biogeochemical effects, because in their models, climate was not dynamically simulated, whereas Sadiq et al. (2017) considered both effects because their model dynamically simulated climate. Moreover, a fourth study (Zhu et al., 2021) that focused on China is currently under review.

P5 L100:

A better justification is needed here to illustrate why this is important to look at. It’s unquantified, but do we really expect the ozone-vegetation feedback via fires is really gonna be important? Any justification for this expectation (and thus the motivation of this paper)? Any comparison with previous work regarding the magnitude of the potential effects?

P8 L160:

The setting of this model using prescribed meteorology needs to be emphasized and contrasted with fully coupled climate-chemistry-vegetation models such as CESM. It should also be emphasized that this model setting only addresses the “biogeochemical” effects, not “biogeophysical” (referring to the points made above).

P9 L181:

Does YIBs actually simulate a multi-layer canopy, instead of a big-leaf canopy? This needs to be clarified. If a multi-layer canopy is represented, the number of layers and other canopy parameter setting needs to be clarified. If not, this line here should be corrected.

P11 L230-241:

An obviously missing element in their model setting and experiments is that fires also damage LAI and canopy height directly, which may only happen only where fires happen but would be the dominant effect (other than ozone damage on plants) there. Fires also influence the long-term recovery and growth of the forests, which of course would also influence ozone. I understand that such an effect is more localized to the forested areas while the ozone-vegetation feedbacks can occur downwind of the forests, the lack of consideration of this necessary pathway should be explained upfront early on. Indeed, this should also be discussed as early as in the introduction.

P13 L285:

It should be clarified that the reductions are consistent with studies/models that used the same ozone damage scheme. It should also be mentioned that some other studies, using other ozone damage scheme, e.g., the Lombardozzi scheme (Zhou et al., 2018; Zhu et al., 2021), may find quite different ozone-induced reductions in GPP.

P14 L303:

The reduction in stomatal conductance mainly follows reduced photosynthesis – this should be clarified. This is obviously missing some newer physiology that people have found recently, e.g., the sluggishness of stomatal responses after ozone damage (Huntingford et al., 2018) that may cause the stomata to be more open under ozone exposure than otherwise. Such missing element needs to be discussed.

P17 L354:

Why does fire emission cause larger ozone-vegetation feedbacks than non-fire sources? It needs to be explained.

P17 L359-363:

The rationale behind needs to be explained in greater detail as well.

P19 L406-409:

This is also related to my comments on P11 L230-241 above. Fires do not only affect BVOC by burning vegetation, it also reduces LAI and the long-term recovery and growth of the forests, thus affect the whole ozone-vegetation interactions in the long term. When a forest is burned, the reductions in LAI, dry deposition, transpiration and BVOC emissions can have effects that last for many years, and this temporal perspective is entirely missing from the current discussion. A more thorough discussion on this missing element, and the implications on the validity and significance of this paper’s results, is warranted.

References:

Huntingford, C., Oliver, R. J., Mercado, L. M., and Sitch, S.: Technical note: A simple theoretical model framework to describe plant stomatal “sluggishness” in response to elevated ozone concentrations, Biogeosciences, 15, 5415–5422, https://doi.org/10.5194/bg-15-5415-2018, 2018.

Wang, L., Tai, A. P. K., Tam, C.-Y., Sadiq, M., Wang, P., and Cheung, K. K. W.: Impacts of future land use and land cover change on mid-21st-century surface ozone air quality: distinguishing between the biogeophysical and biogeochemical effects, Atmos. Chem. Phys., 20, 11349–11369, https://doi.org/10.5194/acp-20-11349-2020, 2020.

Zhou, S. S., Tai, A. P. K., Sun, S., Sadiq, M., Heald, C. L., and Geddes, J. A.: Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health, Atmos. Chem. Phys., 18, 14133–14148, https://doi.org/10.5194/acp-18-14133-2018, 2018.

Zhu, J., Tai, A. P. K., and Yim, S. H. L.: Effects of ozone-vegetation interactions on meteorology and air quality in China using a two-way coupled land-atmosphere model, Atmos. Chem. Phys. Discuss. [preprint], https://doi.org/10.5194/acp-2021-165, in review, 2021.