Phytoplankton size class in the East China Sea derived from MODIS satellite data

Zhang, Hailong; Wang, Shengqiang; Qiu, Zhongfeng; Sun, Deyong; Ishizaka, Joji; Sun, Shaojie; He, Yijun

doi:https://doi.org/10.5194/bg-15-4271-2018

Articles | Volume 15, issue 13

https://doi.org/10.5194/bg-15-4271-2018

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

https://doi.org/10.5194/bg-15-4271-2018

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

Articles | Volume 15, issue 13

Research article

|

13 Jul 2018

Research article |

| 13 Jul 2018

Phytoplankton size class in the East China Sea derived from MODIS satellite data

Hailong Zhang, Shengqiang Wang, Zhongfeng Qiu, Deyong Sun, Joji Ishizaka, Shaojie Sun, and Yijun He

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Final revised paper (published on 13 Jul 2018)
Preprint (discussion started on 05 Feb 2018)

Interactive discussion

Status: closed

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

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RC1: 'Referee Comment for bg-2017-508', Anonymous Referee #1, 25 Feb 2018
- AC1: 'Response to Reviewer #1', Zhongfeng Qiu, 05 Apr 2018
RC2: 'Review report for "Phytoplankton size class in the East China Sea derived from MODIS satellite data" by Zhang et al.', Anonymous Referee #2, 28 Feb 2018
- AC2: 'Response to Reviewer #2', Zhongfeng Qiu, 05 Apr 2018

Peer-review completion

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

ED: Reconsider after major revisions (16 Apr 2018) by Anja Rammig

AR by Zhongfeng Qiu on behalf of the Authors (18 Apr 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 May 2018) by Anja Rammig

RR by Anonymous Referee #1 (16 May 2018)

Suggestions for revision or reasons for rejection

The spectral-based model proposed by Wang et al. (2014) was modified in this study for retrieving PSC in the East China Sea from MODIS data. Internal relationship between PSC and the spectral variability of phytoplankton absorption is the key point for this model. In order to minimize the effect of high noise and low accuracy at shore wavelengths, the authors reconstructed the Rrs spectra by using the multivariate linear relationships at different wavelengths. Based on in situ match-up data analyses, satellite derived PSC compared well with those derived from HPLC pigment composition. Seasonal variability of PSC in the three sub-regions were discussed by considering different environmental factors, which gave us a better understanding of PSC distribution in ECS at synoptic scales. We can see obvious improvement in the revised manuscript.
I suggest minor revision considering the following points:
1. Detailed information for estimating PSC from the DPA approach are required. In this study, Chlorophyll-b was one of the diagnostic pigments of nano-phytoplankton, which is different from that method used by Brewin et al. (2010) for open ocean. More explanations are needed.
2. It’s not surprising to see the poor performance of the model by Brewin et al. (2015) or Sun et al. (2017). There are several points we have to consider. Different criteria for estimating the PSC from the diagnostic pigments were used which may result in large differences in the basic dataset. We also have to consider the regional differences. Did the authors use the model directly? Maybe the coefficients for these models could be locally modified before comparison.
3. General spatial distribution of PSCs seems reasonable. Obvious differences about the seasonal variability of PSCs in three sub-regions were shown in Fig.8 and Fig.9. We can see clear shift of the dominant phytoplankton size class, especially in MSR and KR regions. More explanations about these variabilities with referred to previous work (two of them are listed below) could be very helpful for confirming these results. I think these results could also be highlighted in the abstract.
4. The exact size and location of three sub-regions could be specified by giving the longitude and latitude range, rather than the pixel numbers.
Some references:
Guo, S.J., Y.Y. Feng, L. Wang, M.H. Dai, Z.L. Liu, Y. Bai, and J. Sun, 2014. Seasonal variation in the phytoplankton community of a continental-shelf sea: the East China Sea. Marine Ecology Progress Series, 516 103-126
Liu, X., Xiao, W., Landry, M.R. et al.，2016. Responses of Phytoplankton Communities to Environmental Variability in the East China Sea. Ecosystems , 19: 832-849. https://doi.org/10.1007/s10021-016-9970-5.

Referee Report: PDF

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ED: Reconsider after major revisions (19 May 2018) by Anja Rammig

AR by Zhongfeng Qiu on behalf of the Authors (28 May 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (11 Jun 2018) by Anja Rammig

RR by Anonymous Referee #1 (14 Jun 2018)

ED: Publish as is (29 Jun 2018) by Anja Rammig

AR by Zhongfeng Qiu on behalf of the Authors (01 Jul 2018) Manuscript

Short summary

The PSC model was re-tuned for regional application in the East China Sea, and successfully applied to MODIS data. We investigated previously unknown temporal–spatial patterns of the PSC in the ECS and analyzed their responses to environmental factors. The results show the PSC varied across both spatial and temporal scales, and was probably affected by the water column stability, upwelling, and Kuroshio. In addition, human activity and riverine discharge may impact the PSC dynamics.