Dear authors,

based on my own reading of the manuscript I find the reviewers comments valid and ask you to revise the manuscript accordingly. A more stringent scientific reasoning, as you have already indicated in your responses to the reviewers' comments and including a new (sub)section concentrating on model validation in the main part of the manuscript (rather than the supplementary material) will be required before the manuscript can be considered for publication. Please provide a point-by-point response along with the revised version. The revised manuscript will have to be sent out to the reviewers before a final decision can be made. I look forward to the appropriately revised version of your manuscript.
Many thanks for your effort and best regards,
-Andreas Oschlies

Dear authors,
many thanks for the substantial revision of your manuscript, which has now seen by both reviewers again. While both acknowledge improvements, some concerns (e.g. validation issues, presentation/structure, relation to previously published research, mechanistic explanation) are still not satisfactorily resolved. Both reviewers recommend another revision, and based on my own reading I find their concerns valid and therefore ask you to take all the comments by the two reviewers into account, they are mostly very constructive I think, and to revise your manuscript accordingly.
Best regards,
-Andreas Oschlies

Dear Haiyan Zhang and co-authors,
The two reviewers who assessed the first version of your work have reviewed the revised version. Although they both underline important improvements, they still raise major concerns. Based on that and on his own evaluation, the editor handling your work, Andreas Oschlies, recommends major revisions (please see his comments).

Thank you for your efforts,

Kind regards,

Marilaure Grégoire

Another revision of the manuscript has helped to further improve presentation and scientific content.
This is also appreciated by the reviewer who, nevertheless, raises a few remaining points that need to be resolved:

(i) The simplistic representation of sedimentary oxygen consumption needs to be acknowledged and the statement that sediment oxygen consumption is important for hypoxia, needs to be adjusted.

(ii) Because you chose to separate interannual from intra-seasonal, time scales under consideration should be expressed more clearly throughout the text (e.g. in line 458-460 you presumably refer to intra-seasonal without mentioning any time scale nor change in forcing at all?). Right now the conclusions on intra-seasonal time scales are not overly strong, which might be due to a lack of clarity and an implicit association of variability with interannual variability. I do not ask for a new analysis, but for a more careful presentation.

minor issues:

line 74 please use SI units for O2 concentrations

Fig 7 and Table 1 assume zero lag. Would be interesting to know whether the consideration of a lag led to significant changes.

l. 362 correlation coefficients should be expressed as 0.43 , not 43 % etc.

I hope that these remaining changes can be dealt with without too much trouble and look forward to receiving a suitably revised manuscript.

Best regards,
-Andreas Oschlies

Dear Haiyan Zhang and co-authors,
The revised version of your work has been evaluated by the reviewer. Based on that, Andreas Oschlies, the handling editor, requests further revisions of your work. Please refer to his recommendations.
Kind regards,
Marilaure Grégoire

The authors have addressed all the remaining points and provided appropriate improvements to the manuscript, which I am now happy to accept for publication as is. I thank the reviewers and the authors for their effort and their constructive contributions that have considerably improved the manuscript!
Best regards,
-Andreas Oschlies

Dear Haiyan Zhang and co-authors,
Andreas Oschlies, the handling editor of your work, has evaluated the last version of your manuscript. He is satisfied with your revisions and recommends acceptation of your work.
Then, we are pleased to accept you paper for publication in Biogeosciences.
Thank you so much for your efforts.
Kind regards,
Marilaure Grégoire