Dear authors, co-authors,

I already wanted to provide this editors comment earlier so that you could have potentially included some of these in your response to the reviewer (editors) comments and for the revision of your paper. Unfortunately due to the workload this further feedback just comes after you have provided your response and revision.
Some of these comments from my side also result from some interesting discussions I have had last week visiting some colleagues who also work on ocean-atmosphere exchange processes, in particular O3 and still want to introduce some of the points that come out of those discussions but also want to provide feedback on a couple of issues that already came across reading your ms after its initial submission and add up to the comments provided by the two reviewers.

Pp2; line 30: it is Wesely

Pp3; line 11: I would leave out here the reference to Ganzeveld et al. 2009 since there we actually introduced the more mechanistic model. The one study that was discussed in that paper was the Kuhlmann et al., 2003 reference.

Pp4, line 25 and beyond: “but a detailed testing against deposition data was not reported, presumably because of the lack of suitable data at the time”
I don’t agree with that statement. In the 2009 study we actually show a comparison of the simulated VdO3 and O3 dry deposition fluxes for the measurements that were available that time (Table 2 in Ganzeveld et al., 2009) and where we also evaluated how the comparison improved including the potential role of DOM-O3 chemistry. You are correct that we couldn’t include yet all the results reported in the Helmig et al. 2012 paper that you have applied in your paper but so might like to revise this statement.

Pp6: lne 21: “The deposition velocity is uniformly distributed to all model levels contained within the atmospheric boundary layer”. Reading over this statement it interprets that the removal rate in the surface layer is smaller than the overall deposition rate or is the same deposition velocity used in all layers representing the boundary layer? and is this approach applied to potentially correct for issues on the representation of vertical transport?

Pp 12, line 26: “This is not as…

Pp 16: lines 25 and beyond; in this short discussion on potential issues involved in the role of the reactivity at this point, but actually also further throughout the paper, you only elude on the role of the Iodide whereas the total reactivity might also be strongly dependent on for example some of the DOM-O3 chemistry as discussed in more detail in the Ganzeveld et al., 2009 paper. In the revised paper you now mention explicitly that you have excluded in your study the role of organic compounds in your study. Still I think it would be worthwhile to shortly discuss how inclusion of this feature could further affect the presented modelling results also in comparison to the 1-layer scheme. This chemistry could be especially relevant in the coastal zones but also in regions of strong upwelling with ocean productivity, in some of the colder waters of the Arctic but also in the southern oceans with cold conditions and where your analysis mainly makes a point about seeing there the largest differences between the 1- and 2 layer approach.

Pp16: I noticed that you removed the statement indicating that in the 2009 study we applied the nitrate as a proxy to indeed infer the Iodide concentrations (also since by that time the SST dependence was not yet presented). It seems that you have done so also because of the demonstrated stronger correlation between SST and Iodide. However, I think that it is actually important to explicitly mention this essential difference in the inversion of the Iodide fields comparing the deposition schemes and modelling results. I also agree with one of the reviewers suggestion that it would have been interesting to potentially compare the impact of the differences in inferring Iodide (also including a run with the 2-layer model with Iodide based on nitrate) also because, despite the apparent stronger correlation between SST and Iodide, this feature of getting realistic oceanic biogeochemical boundary conditions for these deposition calculations seems to be a remaining essential challenge also due to limited observations.

The following comment also relates to one of the comments made by reviewer #2. Referring to your discussion on the global and oceanic deposition budget, I noticed that with your global model simulations with an oceanic ozone deposition sink which is 12% of the global sink, you arrive at a flux of about 80 TgO3 yr-1. You discuss that this for the 1-layer model it would be about 19% and for the fixed rc approach about ~21% or so. This would imply a global oceanic O3 deposition budget of 180 TgO3 yr-1 which is substantially smaller than the 300 TgO3 yr-1 global oceanic O3 deposition term presented by Ganzeveld et al. (2009). Is raises a question how to appreciate these differences between the 1- and 2- layer oceanic O3 deposition model recognizing already the fact that there seems to be like a ~factor 2 difference among such global chemistry-climate models inferring this ozone budget term. It also comes back to my remark about the deposition approach in your model using the vd uniformely distributed over all boundary layers. Rather than evaluating the O3 dry deposition velocities, it would be useful to also evaluate the O3 dry deposition fluxes by comparison with the observations. Have you conducted such an evaluation??

So far this number of additional comments that come up reading over again the manuscript, your response and the revision. I am curious to read your response to this last round of feedback on your ms.

Regards, Laurens Ganzeveld

Dear author, co-authors, I have evaluated your response as well as the revisions you made based on the additional comments I provided in an editors comment. It seems now that the remaining open issues have been properly addressed and consequently accept the ms for publication in ACP. Let's see how this publication on oceanic O3 deposition will further stimulate some of these research activities including flux measurements and assessments on the link between ocean deposition and ocean biogeochemistry,

Laurens Ganzeveld