|Review of the revised manuscript "Comparison of ocean vertical mixing schemes in the Max Plank Institute Earth System Model (MPI-ESM1.2)"|
I think the revised manuscript is greatly improved as compared to the previous version in terms of clarity. But I still have a few concerns.
I may misunderstand the main purpose of this manuscript. But based on the title and abstract I was expecting to see a more in depth discussion of the differences among the four vertical mixing schemes and how these differences lead to the differences in the simulated mean climate states in MPI-ESM1.2. However, it looks like that the authors would like to present the differences in the simulated mean climate states with the four vertical mixing schemes on a high level without going too deep into the causes of these differences. This is fair as I understand that it is hard to disentangle the climate responses to the changes in parameterizations in a coupled system. But I would suggest the authors to pay more attention on the differences between the four simulations with different ocean vertical mixing schemes, and perhaps a bit less on the common "biases" of these simulations. Otherwise I don't see much added value of this manuscript to the authors' previous publication Gutjahr et al. (2019), which, if I understand it correctly, is an overview of similar MPI-ESM1.2 simulations with a set of different configurations.
In particular I think there are a few pieces of information missing in the introduction section:
1) What is the main purpose of this study?
2) Why are these four schemes chosen, given the many other choices? Or why do you think a comparison among these particular four schemes in MPI-ESM1.2 is helpful?
3) What do you want to get out of this comparison of the four vertical mixing schemes in MPI-ESM1.2?
Then, in the presentation and discussions of the simulation results, I would suggest the authors to focus more on differences among these simulations. The present discussions appear a bit unfocused to me.
L41-50: A sentence or two on why the four schemes were chosen given these many more may be helpful. Perhaps moving the paragraph of L29-35 here after this paragraph?
L64: "ist" -> "is"?
L69: "modified version PP" -> "modified version of PP"?
L82: What is the main difference from the CVMix version? Is the Marsland et al extension the only difference?
L110: "first" -> "upper"?
L115: Based on Table 1 it looks like you are using PP below the mixed layer for HR_kpp. Does that mean the only difference between HR_pp and HR_kpp is the treatment in the mixed layer? How is the mixing in the mixed layer treated in HR_pp?
L149-150: But it looks like the deep convection in the Labrador Sea is the strongest in HR_ide? What might be the reason?
L171: I can see quite some differences in, e.g., the Eastern and Western Equatorial Pacific and the subtropical regions in the Atlantic?
L182: The simulations are forced by constant 1950s conditions whereas the PIOMAS represent the average of 1979-2005. Do you expect they will match each other if the model is perfect?
L184-186: Are you comparing with HR_pp? HR_ide seems to have an ice edge to the further north.
L188: By TKE here are you referring to both HR_tke and HR_ide?
L204-205: Comparing which vertical mixing schemes?
L206: Fig 8 introduced before Fig 7?
L211-212: What about the salinity bias in the South Pacific?
L213: Is the streamfunction in Fig 7 integrated in the vertical over the full depth, or from the surface to some depth?
L219-220: You can probably see this by looking at vertical sections of the salinity in this region.
L229-231: This reflects one of the issues in this set of simulations. If you run the simulations (forced by constant 1950s conditions) for longer, you might see different patterns of the "biases", right? So how sensible is the magnitude of the "biases" shown here in these figures?
L233: Delete "of"?
L234-237: I’m confused, are you discussing Fig 7 in this paragraph?
L245-248: This paragraph is confusing.
L258-260: I don’t understand this sentence.
L361: Do you mean "warm halocline layer"?
L436: Delete "but"?
L438-439: What do you mean by "in addition, we compare them with control simulations"?
Fig 1: This figure shows the differences between the four vertical mixing schemes in the ocean interior very nicely. I wonder if it is worth to show their differences in the mixed layer as well, which may be more relevant to the ocean surface states such as SST, SSS and MLD.
Gutjahr, O., Putrasahan, D., Lohmann, K., Jungclaus, J. H., von Storch, J.-S., Brüggemann, N., Haak, H., and Stössel, A.: Max Planck Institute Earth System Model (MPI-ESM1.2) for the High-Resolution Model Intercomparison Project (HighResMIP), Geosci. Model Dev., 12, 3241–3281, https://doi.org/10.5194/gmd-12-3241-2019, 2019.