The manuscript is overall much better than the first version and, in my opinion, only requires a few minor adjustments before publications.
The introduction reads substantially better than version 1 and, this time, really sets the stage to an interesting paper. One major improvement over the last version is the way the various experiments are used and presented. This is now much more logical and helpful. There are still a few sections where additional explanations would be desirable (see specific comments), but overall, the structure is good.
I still think that reliance on only the Atlantic data for assessing statistical model fit is a poor choice and this leads to some convoluted explanations in the main text, but this is no a major issue at this point. I respect this is the author’s choice, even I believe it is a bad choice. I would simply suggest that the authors make it as clear as possible throughout the manuscript that all fits pertain to one single section in the Atlantic only.
One remaining frustrating detail is that the authors seem to have replaced the word “realistic” with the word “accurate”. Unfortunately, replacing a word doesn’t fix the problem, which is to overly rely on highly subjective statements of quality. Please reduce this further by being more specific or more quantitative in your statements.
P5, l13, remove “on” from “on shipboard”
P11, footnote (2). Just add that to the main text directly.
P14, l24: “recently measurements” change to “recent”
P15, l16: consider rephrasing this “: very soon the [Mndiss] reaches the typical background concentration”, maybe “ as Mndiss approaches near-constant deep background concentrations quickly such that the NADW plume is no longer discernable.”
Section 3.3, p17. Expand this section – this is interesting. Please provide an interpretation as to why Atlantic value don’t change but Pacific results do.
P18, l15. Table 6 shows a reliability intex of 1.88 for NoThresh, not 2.77.
P17, l20: What is your definition of “reasonably accurate”?
P18, l27: overstatement “only the Reference simulation is accurate”. What is your definition of accurate?
P19, l4-5: I don’t understand the logic behind that argument about “usefulness”: “We think that coupling the model to the sediment would … maybe not that useful, because the sediment source is large at shallow sediments, while most of the Mn burial occurs near the hydrothermal vents”
P19, l10-11: Does the model handle “small” shelf regions well? Can you make any quantitative argument about how well the model resolution handles shelves?
P19 ,l12: Why only report on Slomp’s maximum values?
P19, l16: “out of proportion in some regions of the ocean”. Where is that specifically? Is that only in the Arctic, as alluded to in the next sentences?
P19, l20-21: add a comma in “…Pacific Ocean, where…”
P19, l22: “In the East Pacific Ocean the California Current induces Ekman transport and hence equatorial upwelling”. Very puzzling bit of physical oceanography? Some references in support of that statement would be very welcome. I believe wind induces Ekman transport, not the California current. I’m also not aware of physical theories of equatorial upwelling that argue the California current induces it.
P19, l23: “upwelling from OMZ sediments”. Maybe “upwelling of water that has been in contact with OMZ sediments”
P19, l24: “This is partly captured by our model”. Which part?
P19, l25: “In the South Pacific Ocean this effect is more clear in the data of Resing et al. (2015) (Fig. 8a,b, East Pacific around 20S).”… and in the model?
P19, l27-29: Better would be to provide a back of the envelop estimate of how much bias may come from not representing fluxes from OMZ sediments.
P20, l21: “and especially at low latitudes”. Please substantiate this with a few sentences. The previous discussion was all about the Southern Ocean, not on low latitudes”
P20, l23: What is “the most settling Mn”? Do you mean the particulate Mn fraction that contributes most to the sinking Mn flux is from biological particles?
P20, l28: include, not includes
P22, l29: “because Mn redox does not depend on O2”. Rewrite sentence. What is “Mn redox”?
P22, l31-43: “…For this reason we have not included a dependency on [O2] to the model….” Consider rewriting these few sentences in a less convoluted way.
P24, l6: remove “e.g.” – say what you mean in words instead.
P25, l3: “for an accurate simulation of [Mndiss]”. What is your definition of accurate? Replacing “realistic” with “accurate” doesn’t remove the problem of relying on subjective statements.
Appendix A, p27,l3: do you refer here as the “Pearson correlation coefficient”? please specify.
Appendix A – Table 6. Why are there only errors for the Reference case and not all cases? For comparison purposes, errors should be calculated on all cases.
Figure 7, caption. What do you mean by the word “by in “the by red” or “the by blue” lines? Probably remove this. Also, would be good to make these lines thicker on the figure. They are very thin, even when the figure is full screen.
Figure 8: x-axis labels and sub-plot titles overlap. Fix spacing.
Figure 5 and 9. Choose a consistent name between GIPY5 or GIPY5_e.
Figure 13, explicitly state in the caption if relative difference is (ref-low hydro)/low hydro or (ref-low hydro)/ref?
Figure 16, make the colored lines thicker