Dear Authors,

Your manuscript has now received comments from 4 experts in eddy-covariance data acquisition and processing, of which three suggest substantial improvements are needed, and one suggests rejection. A common theme across the reviews is that the manuscript is somewhat misleading in terms of the extent of the problem and overlooks the long-history of efforts to address it. The reader comes away with the impression that timing errors of the magnitude reported here could affect the majority of eddy-covariance records, and a few of the reviews had the impression that you were advocating analog-only solutions.

Some points to help you address these concerns:
- You should make very clear throughout the manuscript (especially abstract, intro, discussion and conclusions) that your work applies only to in-house developed EC systems. It would also be great if you could give a sense of what proportion of EC systems are in-house. I understand this is difficult, but it is important to give the reader a sense of whether the vast majority of systems are commercial, or in-house.
- I understand you want to exclude commercial solutions, but I do not think that makes sense. You are highlighting a problem to which a solution has been developed, and it would be much more helpful to the community to direct readers to those solutions. You could however use the magnitude of the problem to call on commercial organizations to open source their solutions, or at the very least to highlight that the degree of implementation across commercial platforms is not quantifiable (as you claim). This lack of an acknowledgement of existing solutions came up a lot with the reviewers.
- You mention that most solutions are not scalable to other species than CO2 and H2O. What about CH4, for which Eugster and Plüss (2010) present a fault tolerant system? The measurement of other species (e.g., H2, N20, O3, BVOCS), remains very rare across global networks, which brings us back to the question of how widespread the issue of timing errors is.
- it would seem pertinent to put the errors reported here in the context of other sources of error, as suggested by the reviewers, to give the reader a sense of magnitude.

I hope these suggestions help you to improve the manuscript. It is likely that another round of reviews will be needed before being able to make a decision on publication.

I look forward to receiving your revised manuscript.
All the best,
Trevor

Dear Authors,

Thank you for your efforts to incorporate the reviewers' comments, as well as the short comments submitted during the discussion phase. The changes you have made have greatly improved the manuscript, making clear that you are specifically addressing an issue of in-house systems, and acknowledging previous efforts in this area. I am happy to say that we can now accept your manuscript for publication in Biogeosciences. Thank you for all your efforts and best wishes for your future work.

Trevor