General Comments:

This paper examines the concept of “self-healing” and “reverse self-healing” and proposes a more general mechanism called “photochemical adjustment”. This adjustment can be stabilizing or destabilizing. Stabilizing adjustment is simply showing that the original ozone perturbation is damped top-down. Destabilizing adjustment is more complex and depends on how the top-down enhancement of the UV flux interacts with the odd-oxygen loss process. The authors discuss how the magnitude of the ozone slant column determines if a photochemical adjustment is stabilizing or destabilizing. I also found this paper interesting in that the concept of “self-healing” has been around since Johnston (1972), but a quantitative theory on the “self-healing” process has not been examined in detail till this work. I found this paper to be clearly written. The concepts are laid out in a readable manner (if anything a bit redundant). This work will not only be useful for perturbation studies of the present atmosphere but also for early Earth chemistry studies.

I highly recommend this paper to be published!

Specific Comments:

Section 1. (no action needed)

The authors do a nice job of summarizing the discussion of “self-healing” in the literature.

Section 2. (no action needed)

The authors clearly describe the regimes where “photochemical adjustment” operates either in a stabilizing or destabilizing manner. Destabilization is not an expected result and can only be “distinguished by the magnitude of the response without a quantitative theory.

Section 3. (suggestion made)

This section uses a chemistry-climate model to examine the net ozone production rate (production–loss terms). E.g., if the net ozone production is positive for an overhead positive perturbation than the photochemical adjustment is destabilizing. Using the chemistry-climate model is the step needed to quantify the photochemical adjustment theory. It was nice to see you describe what the linear ozone model includes in Equation 1 and show the A6 equation plotted in Figure 3. It was also interesting that a simpler Chapman-only chemistry representation is consistent above 40km.

Interpretation of Figure 3. When one looks closely at the zero contour in Figure 3a and 3b, the altitude where destabilization starts is much lower in Figure 3a than in 3b suggesting the additional odd-oxygen families (NOx, HOx, ClOx, etc…) are important for defining this threshold. I don’t believe you make this point in this section. You may also want to add a new Figure (3c) that shows a profile of equation A6 for both chemical mechanisms.

Section 4. (suggestion made)

This is a very clever approach in equation (2) to derive “photochemical adjustment”. One suggestion that would make reading your logic on photochemical adjustment easier would be to not include the equations in the sentences of the document (page 10) but delineate them as you did equation (3). This is purely a style suggestion.

Section 5. (no action needed)

Very clearly written. Excellent job of taking the reader through each step of deriving the photochemical adjustment in the Chapman Cycle.

The main difference between Figure 4 and Figure 6 seems to be in the perturbation response to cooling (not ozone response to depletion). As you state in lines 450-453 “reverse self-healing is stronger in the Off-line Cariolle v2.9 emulator than in the Chapman Cycle, suggesting a role for non-Chapman stabilizing processes including catalytic chemistry and transport.” It is nice to know that detail chemistry plays a role here!

Section 8. (suggestion made)

It is not clear to me how one can derive the role of transport in photochemical adjustment. Your comments in this section do not seem to add any clarity on how this could be derived. Can you expand on what “further work” would look like or can you at all estimate what the maximum role of transport would play in your current analysis?

Section 9.

Nice summary. It would be very interesting to complete this analysis in an early Earth atmosphere.

See attached file