Comment on bg-2021-116 Anonymous Referee # 1 Referee comment on " Geophysical and biogeochemical observations using BGC Argo floats in the western North Pacific during late winter and early spring , Part 2 : Biological processes during restratification periods in the euphotic and twilight layers

Sukigara and co-authors investigate the effect of passing storms on the production of organic matter and its fate once exported into the mesopelagic, using 2 BGC-Argo floats deployed in the western North Pacific. Main conclusions are (1) storms induced a net community production of 126-664 mg C m-2 d-1 and (2) the subsurface deviation of POC/O2/N ratios from Redfield ratios is due to remineralization of DOC which is assumed to be the main substrate. I think that the figures and results presented in the manuscript do not support these conclusions. Main issues are:

Sukigara and co-authors investigate the effect of passing storms on the production of organic matter and its fate once exported into the mesopelagic, using 2 BGC-Argo floats deployed in the western North Pacific. Main conclusions are (1) storms induced a net community production of 126-664 mg C m-2 d-1 and (2) the subsurface deviation of POC/O2/N ratios from Redfield ratios is due to remineralization of DOC which is assumed to be the main substrate. I think that the figures and results presented in the manuscript do not support these conclusions. Main issues are: (1) BGC-Argo floats are not Lagrangian floats, so sections of oceanic properties have to be interpreted with caution. Observed changes are not necessarily temporal changes, as the float can move across different water masses. This is particularly true in highly energetic regions such as the Kuroshio Extension region. Calculating production or consumption rates requires that the floats track the same water masse. Here, the authors acknowledge that for 3 of the 4 events analysed, floats may have been tracking different water masses due to the presence of eddies. So how can we trust the production/consumption estimates? Also, when calculating these rates, it is worth mentioning that you neglect diffusive fluxes of O2 and NO3.
(2) POC production is not equivalent to net community production (NCP), as a fraction of the fixed carbon is released as DOC (22 to 40% in the North Atlantic, Alkire et al. 2012). NCP is also different from NPP (NCP=NPP-heterotrophic respiration), so it makes no sense to compare your POC production to NPP. Also, you argue that deviation from the Redfield ratio in the mesopelagic is due to remineralization of DOC (and not only POC). But the same argument stands for the C/N ratio in the surface layer. Production of POC alone is not supposed to reflect the total N consumption. See also comments on the Redfield ratio in the section below.
(3) The authors refer throughout the manuscript to temperature, salinity, wind, net heat flux and SSH, but none of these variables are shown. I understand that some of these variables are probably shown in the companion paper, but it is a bit frustrating not seeing them. You could at least show temperature and salinity sections.
(4) Regarding the form, I think the results section contains only 'basic' observations/results, while most important results are drowned in the discussion. The most interesting figure (figure 7), from my point of view, is only introduced and discussed in the conclusion. Also, I think a statement of the objectives of this study is missing in the abstract. I found the quality of the writing to considerably decrease over the course of the paper. I had difficulties to understand some of the discussion/conclusion sentences. The writing clearly needs to be improved. lines 208-209: phytoplankton stock can also increase during winter mixing, not only once mixing ceases. This is not visible from Chla concentration records due to dilution when the MLD deepens, but it is from depth-integrated biomass records.
lines 218-221: You are comparing local POC to Chla ratios with worldwide Cphyto to Chla ratios. That makes no sense (average phyto contribution to POC is ~30%). It is a weak demonstration that Cphyto is correlated to POC. I recommend the authors to refer to publications that investigated the Cphyto-POC(bbp) relationship (Behrenfeld et al 2005, Martinez-Vincente 2012,2013. lines 352-353: What is a "stable" water mass? What do you mean? Also, see my previous comments about the Redfield ratio.
Most of the sentences in the conclusion are not clear and have to be reformulated.