The seasonal cycle of pCO2 and CO2 fluxes in the Southern Ocean: diagnosing anomalies in CMIP5 Earth system models

Mongwe, N. Precious; Vichi, Marcello; Monteiro, Pedro M. S.

doi:https://doi.org/10.5194/bg-15-2851-2018

Articles | Volume 15, issue 9

https://doi.org/10.5194/bg-15-2851-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

The 10th International Carbon Dioxide Conference (ICDC10)...

https://doi.org/10.5194/bg-15-2851-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 9

Research article

|

15 May 2018

Research article |

| 15 May 2018

The seasonal cycle of pCO₂ and CO₂ fluxes in the Southern Ocean: diagnosing anomalies in CMIP5 Earth system models

N. Precious Mongwe, Marcello Vichi, and Pedro M. S. Monteiro

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Final revised paper (published on 15 May 2018)
Supplement to the final revised paper
Preprint (discussion started on 26 Sep 2017)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'SST-CO2 Flux correlations', Anonymous Referee #1, 27 Oct 2017
- AC1: 'Rebuttal document for referee 1', Precious Mongwe, 24 Jan 2018
RC2: 'review of Mongwe et al', Anonymous Referee #2, 31 Oct 2017
- AC3: 'Rebuttal document for referee 2', Precious Mongwe, 24 Jan 2018
RC3: 'Comments Rev#3 Mongwe et al., 2017', Anonymous Referee #3, 06 Nov 2017
- AC2: 'Rebuttal document for referee 3', Precious Mongwe, 24 Jan 2018

Peer-review completion

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

ED: Reconsider after major revisions (25 Jan 2018) by Katja Fennel

AR by Precious Mongwe on behalf of the Authors (06 Mar 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (07 Mar 2018) by Katja Fennel

RR by Anonymous Referee #1 (07 Mar 2018)

RR by Anonymous Referee #3 (22 Mar 2018)

Suggestions for revision or reasons for rejection

Overall Statements:

The revised manuscript ”Mechanisms of the Air-Sea CO2 Flux Seasonal Cycle biases in CMIP Earth Systems Models in the in the Southern Ocean” by N.P. Mongwe, M. Vichi, and P.M.S Monteiro has improved substantially.
In particular my main points to augment Table 1 and additional studies on model results are now included in the manuscript.
The authors added a valuable Synthesis chapter. There they strengthened a second item, which focusses on the simulated homogeneity of the fluxes in the different basins differing from observations.
On the other hand the text still does not give information about model characteristics which may be responsible for exaggerated SST or DIC sensitivities on FCO2 in the different models.
It’s common practice to answer every question or remark of the reviewer. This has not been done. In some cases my item has been ignored, in some cases it has been accounted for. This is not good practice.
Please discuss with the reviewer and, in case of text change, give a note where and how the text has been improved.
This manuscript is still written very sloppily. This has to be improved still substantially.

Detailed remarks:

Homogenise the writing of in-gassing/ingassing and out-gassing/outgassing
Give the method of air-sea flux parameterization within the text.
Line 2: better “Earth System Models”, not “Earth Systems Models” .
The abstract needs to be shortened.
Table 1 contains only 7 models.
L 48 Sarmiento et al., 2004 ref missing
L 53 Son and Gerber 2010 ref missing
L 63 Tab 2 shows that the models do not agree.
L 124 Landschutzer 2013 ref missing
L 183 Vichi et al., 2007 missing in ref list.
L 213 Wanninkhof et al 2010 ref missing
L 249 a word is missing
L 258 Something wrong with the first subscript “averag”
L 265 Wanninkhof et al 2013 ref missing
L 282 define n
L 331, 333 REMSE
L 333 PCC(CESM1-BGC) = 0.47
L 359 a word is missing
L 369 Antarctic Zone March-July change sign. Therefore say “weakening of uptake or an increase of outgassing”
L 402ff The word “however” does not fit here.
L 543 “shows”
L 596 – 597 I cannot see this.
L 619 Dec-Feb is not Australian winter
L 637 say “primary production enhances the ..”
L 703 Do not cite unpublished papers
L 915, 952, 994 add an empty line
Fig. 1 Figures and inscriptions are too small
Fig. 2 Authors ignored the notice to show the model memberships to group SST or group DIC
Fig. 10 shows new patterns compared with the old manuscript, why?
Fig. 10 legend: still wrong units

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ED: Publish subject to minor revisions (review by editor) (30 Mar 2018) by Katja Fennel

AR by Precious Mongwe on behalf of the Authors (12 Apr 2018) Manuscript

ED: Publish as is (17 Apr 2018) by Katja Fennel

AR by Precious Mongwe on behalf of the Authors (18 Apr 2018) Manuscript

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Short summary

Here we analyze seasonal cycle of CO₂ biases in 10 CMIP5 models in the SO. We find two main model biases; exaggeration of primary production such that biologically driven DIC changes mainly regulates FCO₂ variability, and an overestimation of the role of solubility, such that changes in temperature dominantly drive FCO2 seasonal changes to an extent of opposing biological CO₂ uptake in spring. CMIP5 models show greater zonal homogeneity in the seasonal cycle of FCO₂ than observational products.