CITRATE 1.0: Phytoplankton continuous trait-distribution model with one-dimensional physical transport applied to the North Pacific

Chen, Bingzhang; Smith, Sherwood Lan

doi:https://doi.org/10.5194/gmd-11-467-2018

Articles | Volume 11, issue 1

https://doi.org/10.5194/gmd-11-467-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/gmd-11-467-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 11, issue 1

Model description paper

|

01 Feb 2018

Model description paper |

| 01 Feb 2018

CITRATE 1.0: Phytoplankton continuous trait-distribution model with one-dimensional physical transport applied to the North Pacific

Bingzhang Chen and Sherwood Lan Smith

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Final revised paper (published on 01 Feb 2018)
Preprint (discussion started on 02 Jun 2017)

Interactive discussion

Status: closed

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

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EC1: 'Revision number', Andrew Yool, 09 Jun 2017
- AC2: 'Response to the comment by Dr. Andrew Yool', Bingzhang Chen, 23 Oct 2017
RC1: 'Manuscript review', Anonymous Referee #1, 10 Jul 2017
- AC3: 'Response to Reviewer #1', Bingzhang Chen, 23 Oct 2017
RC2: 'Review of gmd-2017-104', Anonymous Referee #2, 12 Jul 2017
- AC4: 'Response to Reviewer #2', Bingzhang Chen, 23 Oct 2017
SC1: 'Code Standard', Lutz Gross, 12 Jul 2017
- AC1: 'Response to the comment by L. Gross', Bingzhang Chen, 23 Oct 2017
RC3: 'Review of « CITRATE 1.0: Phytoplankton continuous trait-distribution model with one dimensional physical transport applied to the Northwest Pacific » by Bingzhang Chen and S. Lan Smith.', Anonymous Referee #3, 27 Jul 2017
- AC5: 'Response to Reviewer #3', Bingzhang Chen, 23 Oct 2017

Peer-review completion

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

AR by Bingzhang Chen on behalf of the Authors (23 Oct 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (07 Nov 2017) by Andrew Yool

RR by Anonymous Referee #2 (13 Nov 2017)

Suggestions for revision or reasons for rejection

The lognormal distribution is a fundamental assumption in the authors’ model. In their revised manuscript, they concede that it is also an unusual one. It is perfectly fine to say that the lognormal can be fit well to empirical data (e.g. Quintana et al. 2008, though another citation or two here would be nice) and has been used in other continuous size models and therefore is used here. However, the mathematical arguments used for why the lognormal was used instead of the power law are uncompelling and/or incorrect.

The authors say that the power-law distribution does not have an upper or lower limit on size, whereas the lognormal does; this is wrong. Power laws are supported (i.e. have non-zero probability density) on the range [x_min, infinity), whereas lognormals are supported on the range [0, infinity), so these distributions are not different in this regard. In fact, it is much more common to specify an upper cutoff on power laws via an exponential truncation than it is for a lognormal. It is quite easy to calculate the mean and variance of a power law, so these are bad examples of mathematical manipulations for which the power law is hard. The power law also has zero probability of negative size; actually if x_min for the power law can be set to the size of the smallest phytoplankton in the system (e.g. Pro), which means that the power law has a zero probability for a cell smaller than x_min, while the lognormal always has a nonzero probability for arbitrarily small phytoplankton. The skewness of the log-size distribution discussed by the authors is further evidence for the power law potentially giving better results than the lognormal.

It’s fine to justify the lognormal by citing that it can be fit to data well and has been used in continuous size models, but the other arguments for its use should be reconsidered, and the authors should be clear that their model hinges upon this unusual, even if justifable, assumption. I recommend the authors read the paper “Power laws, Pareto distributions, and Zipf’s law” by M. E. J. Newman, which gives a clear description of many of the relevant mathematical properties of power laws.

All other changes I found satisfactory!

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RR by Anonymous Referee #3 (14 Nov 2017)

ED: Publish subject to minor revisions (review by editor) (17 Nov 2017) by Andrew Yool

AR by Bingzhang Chen on behalf of the Authors (27 Nov 2017) Author's response Manuscript

ED: Publish as is (05 Dec 2017) by Andrew Yool

AR by Bingzhang Chen on behalf of the Authors (19 Dec 2017)

Short summary

Marine phytoplankton accounts for half of global primary production. Phytoplankton size is an important trait affecting its fitness and ecosystem functioning. We have developed a plankton model with continuous size distribution for phytoplankton and applied it in the North Pacific. This model is able to capture the general patterns of phytoplankton size distribution in the real ocean and can be used for understanding the mechanisms controlling phytoplankton size structure and diversity.