Variations in the summer oceanic <i>p</i>CO<sub>2</sub> and carbon sink in Prydz Bay using the self-organizing map analysis approach

Xu, Suqing; Park, Keyhong; Wang, Yanmin; Chen, Liqi; Qi, Di; Li, Bingrui

doi:https://doi.org/10.5194/bg-16-797-2019

Articles | Volume 16, issue 3

https://doi.org/10.5194/bg-16-797-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/bg-16-797-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 16, issue 3

Research article

|

13 Feb 2019

Research article |

| 13 Feb 2019

Variations in the summer oceanic pCO₂ and carbon sink in Prydz Bay using the self-organizing map analysis approach

Suqing Xu, Keyhong Park, Yanmin Wang, Liqi Chen, Di Qi, and Bingrui Li

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Final revised paper (published on 13 Feb 2019)
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Preprint (discussion started on 19 Jul 2018)
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Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of Xu et al: Variation of Summer Oceanic pCO2 and Carbon Sink in the Prydz Bay Using SOM Analysis Approach. Submitted to Biogeosciences', Anonymous Referee #1, 06 Aug 2018
- AC3: 'Responses to Referee1', Suqing Xu, 22 Oct 2018
RC2: 'Review of 'Variation of Summer Oceanic pCO2 and Carbon Sink in the Prydz Bay Using SOM Analysis Approach'', Anonymous Referee #2, 07 Sep 2018
- AC2: 'Responses to Referee2', Suqing Xu, 17 Oct 2018
- AC4: 'Responses to Referee2', Suqing Xu, 22 Oct 2018
AC1: 'Responses to Referee1', Suqing Xu, 17 Oct 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (23 Oct 2018) by Christoph Heinze

AR by Suqing Xu on behalf of the Authors (15 Nov 2018)

ED: Referee Nomination & Report Request started (27 Nov 2018) by Christoph Heinze

RR by Anonymous Referee #1 (10 Dec 2018)

Suggestions for revision or reasons for rejection

Dear authors,

In my initial assessment I raised 4 main points concerning methods and data handling, representation of uncertainty and validation. I am happy to say that you have well dressed most of the points raised. In particular, I appreciate that you now add uncertainties to all numbers (I suggest to even remove "mildly increased" based on the uncertainty). Furthermore data handling is much clearer now. Lastly, thank you for adding the cruise information from SOCAT.

Overall, I believe the manuscript is technically sound and the results are well put in context. Therefore, I think the manuscript can be published after fixing a few remaining issues:

.) Methods: While the language is much simpler now and readability has improved, it still reads very difficult and it is certainly still the weakest bit. It is important for the reader to know why the inputs are in vector form. Between what are Euklidian distances calculated? What is a winning neutron. Maybe add a simple example with real data. Imagine and input vector (now with values I made up) with SST=3, SSS=32, CHl=1, MLD=10 and 2 neurons on the map with values (4,30,0.5,5) and (5,35,0,100) respectively. What is the winning neutron? after you have identified the winning neutron, what happens in step 1? and what happens in step 2? Then the link to the geography is also more visible, because the input vector values belong to a certain point in space, etc. That would be my suggestion here.

.) On line 142-144 I read: "The solubility of CO2 is affected by temperature and salinity in the water as well as biological activities, such as phytoplankton taking up CO2 through photosynthesis and organisms releasing CO2 through respiration (Chen et al., 2011)." - I suppose this is a mistake from the authors (maybe awkward phrasing) as biology is not influencing the solubility.

.) Throughout the manuscript spaces are missing (see as example abstract line 15 and line 27 last word(s) of the line. This is reoccurring but nothing major.

.) lines 31-32: This is still awkwardly phrased as carbon uptake implies that the flux is from (and not "to or from") the atmosphere. Best is to remove the phrase "during the transport of CO2 to or from the atmosphere" as a whole.

.) line 88: satellites actually do measure CO2 now - just not in the ocean (see GO-sat or OCO-2). So please say "measure sea surface pCO2"

.) line 139: remove of carbon cycling.

.) line 169-170: please add a reference of some more text on the different methods. (better a reference)

.) line 250: explain the Kriging method? or add a reference

.) line 473: replace "could be" with "can be" - you just did.

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ED: Publish subject to minor revisions (review by editor) (12 Dec 2018) by Christoph Heinze

AR by Suqing Xu on behalf of the Authors (22 Dec 2018)

ED: Publish as is (14 Jan 2019) by Christoph Heinze

AR by Suqing Xu on behalf of the Authors (20 Jan 2019) Manuscript

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Short summary

In this study we applied the self-organizing map (SOM) method to estimate the oceanic pCO₂ in Prydz Bay derived from its main controlling factors. The RMSE of the SOM-derived pCO₂ was 22.14 µatm compared to SOCAT datasets. Our results showed that the monthly averaged uptake of atmospheric CO₂ for February 2015 was 23.57±6.36 TgC. Strong potential anthropogenic CO₂ uptake in the shelf region will enhance ocean acidification (OA) in the deep water of Prydz Bay and subsequently affect deep OA.

Variations in the summer oceanic pCO2 and carbon sink in Prydz Bay using the self-organizing map analysis approach

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Variations in the summer oceanic pCO₂ and carbon sink in Prydz Bay using the self-organizing map analysis approach