Dear Dr. Zhang and co-authors,

Thank you for submission of your revised manuscript. Referee #1 is generally satisfied with your revisions, though some minor issues remain. The referee described those in the attached referee report.

I agree with the referee and think the manuscript is almost there. I did go through the manuscript and provide minor and technical comments below. Please account for the comments by the referee and me, and submit your final version of the manuscript

You are using data from other sources, e.g. satellite data from Copernicus and NASA. Please check and confirm whether you fulfill the fair data use statement and whether the acknowledgment of the data use is according to the request by the data providers.

L42-44 “NCP is equivalent to the rate of organic carbon export and transfer up the food web, which can quantify the strength of biological pump (Lockwood et al., 2012).” It is not clear to me what “transfer up the food web” means, as this is also compared and stands besides carbon export. After the comma, I suggest: and is a measure for the strength of the biological pump (Lockwood et al., 2012).

L44-45 “Dissolved oxygen-to-argon ratio (O2/Ar) has been developed as a proxy for NCP …” I think this requires some more explanation why this is the case.

L56-57 “in global NCP data sets” It was not clear to me that these exist. Please add a reference.

L59 “extremely complex ecological characteristics” It is not clear to me what that implies. Why is it more complex than other regions? Please explain or tone down.

L72 “during its long residence time in the SCS” Please be more specific; how long?
L127 If you measure concentrations, please indicate that here.

L129-131 Are there any cruise reports that could be cited? Do the cruises have EXPO codes?

L152 Please indicate what is measured here of O2, Ar and CO2: concentration, partial pressure?

L156 delete “down during this cruise”
L264 delete “In addition,”

L295-296 Change to: … of the two cruises are shown in Tables 1 and 2.
L299 delete “reasonable”

L303-304 delete “shallower than that of October 2014”
L357-358 Please explain why you took these transects. Why not take transect 4, which was sampled in both years.

L530 I suggest: The amount of light may also play a role in the extent of primary production. (that light play a role in primary production is trivial)

Table 1 Please use data format like 13 Oct 2014
Figure 2 Please delete PSU at the salinity panel
Figure 3 Please delete PSU at the salinity panel

Figure 5a Please delete PSU at the salinity panel
Figure 6a Please delete PSU at the salinity panel
Figure 7 The labels at the axes are too small. Please make them larger for better readability.

Figure 8a Please delete PSU at the salinity panel
Figure 9b and 9d Please delete PSU at the salinity panel

With best wishes
Mario Hoppema