The OMZ and nutrient features as a signature of interannual and low-frequency variability in the Peruvian upwelling system

Graco, Michelle I.; Purca, Sara; Dewitte, Boris; Castro, Carmen G.; Morón, Octavio; Ledesma, Jesús; Flores, Georgina; Gutiérrez, Dimitri

doi:https://doi.org/10.5194/bg-14-4601-2017

Articles | Volume 14, issue 20

https://doi.org/10.5194/bg-14-4601-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/bg-14-4601-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 20

Research article

|

19 Oct 2017

Research article |

| 19 Oct 2017

The OMZ and nutrient features as a signature of interannual and low-frequency variability in the Peruvian upwelling system

Michelle I. Graco, Sara Purca, Boris Dewitte, Carmen G. Castro, Octavio Morón, Jesús Ledesma, Georgina Flores, and Dimitri Gutiérrez

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Final revised paper (published on 19 Oct 2017)
Preprint (discussion started on 15 Jan 2016)

Interactive discussion

Status: closed

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

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RC1: 'Review of the manuscript bg-2015-567', Anonymous Referee #1, 19 Feb 2016
- RC2: 'Review manuscript bg-2015-567', Anonymous Referee #2, 04 Apr 2016
AC1: 'Answer for referees comments and relevant short comments- bg/2015-567', Michelle Graco, 09 Jun 2016

Peer-review completion

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

ED: Reconsider after major revisions (11 Jun 2016) by Gerhard Herndl

AR by Michelle Graco on behalf of the Authors (14 Sep 2016) Author's response

ED: Referee Nomination & Report Request started (20 Sep 2016) by Gerhard Herndl

RR by Anonymous Referee #2 (09 Oct 2016)

RR by Anonymous Referee #1 (27 Oct 2016)

Suggestions for revision or reasons for rejection

Review of the manuscript bg-2015-567: The OMZ and nutrients features as a signature of interannual and low frequency variability off the Peruvian upwelling system

by M. Graco, S. Purca, B. Dewitte, O. Moron, J. Ledesma, G. Flores, C. Castro and D. Gutierrez

General comments:
The revised manuscript by Graco et al. has improved compared to the first version. However, there are still some shortcomings which need to be solved before the manuscript can be published.
The connection of the measurements to El Nino and La Nina periods is weak and should be strengthened (see below).
Very disappointing is the fact that none of the 7 !!! co-authors seemed to have looked carefully at the revised manuscript (see below) and left the work for the reviewers as was the case already at the first version.
The English is still bad (I know all authors are no native English speakers, but some help should be searched to make the manuscript better readable).
I recommend revision of the manuscript.

Specific comments:

So far the authors missed the opportunity to well relate the measurements to the El Nino and La Nina periods. In line 242 a 1997-1998 El Nino event and a 1999-2001 La Nina event are mentioned but these events are not clearly defined and other weaker events are not really referenced. According to the ONI index El Nino’s during the time period presented are: 5/97-5/98 (defined as strong), 6/2002-2/2003 (moderate), 7/04-4/05 (weak), 9/06-1/07 (weak), 7/09-4/10 (moderate) and La Ninas 7/98-3/01 (moderate), 8/07-6/08 (moderate), 7/10-4/11 (moderate) and 8/11-3/12 (weak). These events are well visible in the parameter distribution, especially in the N deficit and the 15°C time series. Hence the El Nino and La Nina time periods should be mentioned in the text and related to the figures instead of listing some years with deepening of the thermocline and mention a coincidence with El Nino conditions (lines 233 to 237). In line 302 the end of 2011 was described as strong La Nina condition, but according to the ONI index it was only a weak La Nina.

Here is a list of errors which a co-author should have noticed in case of reading the manuscript:
-line 250 Figure 3a. This is still a reference from the first version of the manuscript, now it is Fig. 2c. Similar on line 297 it has to be figure 2 not figure 3.
- Line 316: ‘see horizontal lines in figure 6a,b’. In the revised version there are no horizontal lines marked for the standard deviation as had been in the first version of the manuscript.
Line 345: ‘Z_ZMO (Fig. 6 d)’. Figure 6d is Z_OMZ.
- Line 359: ‘Figure 7b’. In Figure 7 no a,b,c, are marked.
- Line 438: In the reply-letter it is stated that the units will be used always the same, but in line 438 and 796 the unit for oxygen are different compared to the text.
- Figure 6 legend is not correct, (b) is now (c); (c) is now (d), (d) is now (e). Figure legend should be adjusted when the figures modified.
- Figure 7 legend: As mentioned above, no a, b, c is marked in the figure but mentioned in the legend.
- The author wrote in the reply-letter that repetition of definitions were removed. However, ESSW (line 220) was already defined in line 63, SSW (line 254 and line 426) already in line 227, IEKW_1 and IEKW_2 (line 311) already in lines 189/190, while CTW (line 521) is not defined.
- References were not checked: Line 464, there is no Naqvi 1991 in the reference list (only Naqvi and Noronha 1991) line 465 no Codispoti et al 1985 (only Codispoti and Christensen 1985), line 468 no Morales et al 1996. Kalvelage et al. 2013 in the reference list is not cited in the text.

In the abstract (line 30) acidic oxygen minimum Zone is mentioned. In the entire text acidic is not mentioned again. Even if not investigated in this manuscript it should be briefly mentioned in the longish general review.
May be define SST in line 89.
Line 123 ‘20 nm’ is strange, better write ‘20 nm off the coast’.
Line 140: I don’t understand the meaning of ‘of the Oxygen Minimum Zone- OMZ and changes…’
Line 221 ‘during summer and spring periods’, mention austral summer and austral spring as you do later in the text.
Line 227-228: SSW can’t ‘penetrate into the coast’, may be write ‘penetrates into the near-coastal area’ or whatever you like to describe.
Line 258: Better include ‘depth’ after ‘thermocline’.
Define ’N.S’ in line 262 and in the header of table 2.
Line 320: ‘delayed by 1 month’, Where can I see this?
Line 692: As I am not able to access all the grey literature listed in this manuscript, is ‘3°N’ correct, as the title states costa peruanu, and the Peruvian coast starts south of ~3°S?
Line 775: Define E and C in the table header and not only in the text.
Figure 1 legend: Mention station 4 as 12°02’S; 77°29’W as in the text, not only by one geographical coordinate.
Figure 2 legend: Mention 15°C marked in Figure 2a to indicate the lower thermocline limit. In the figure the numbers are difficult to read.
Figure 3a: The numbers are difficult to read. May be describe in the figure legend the curves, e.g. 15°C (solid black line), etc.
In Figure 4 legend it is stated that that the oxylines 22.5 and 45 are included in the figure; I can’t find them in the figure.
Why is there a black line in Figure 5 at 60 m depth?
Figure 6: Remove the headers of frames f to j. Always starting the header with c) and using different abbreviations than in frames a to e (e.g. Ndef and N50) is misleading.

Technical corrections:
It would be good to prepare a revised version according to BG manuscript preparation requirements:
On the title page all authors should be listed with first and last names (not only at the author’s addresses).
In the references journal names should be abbreviated according to ISI Journal Title Abbreviation Index….if the abbreviation is not known use the full title: The references are a wide mixture in style and should be presented according to the BG style. E.g. line 585 ‘Progress in Oceanography’, line 587/8 ‘Prog Oceanogr.’ Line 706/7 ‘….kelvin wave JGR: oceans’ etc.

Authors are encouraged to add a section ‘Authors contribution’. Given that the co-authors did not read the manuscript, it would be interesting to see what their contribution was.
Authors are required to provide a statement on how their underlying research data can be accessed. Such a statement should be added to the final version in case of publication.
Why is part of the text bold e.g. lines 451/452, I think BG will not print bold parts in the middle of the text.

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ED: Reconsider after major revisions (30 Oct 2016) by Gerhard Herndl

AR by Michelle Graco on behalf of the Authors (27 Apr 2017) Manuscript

ED: Referee Nomination & Report Request started (22 May 2017) by Gerhard Herndl

RR by Anonymous Referee #1 (02 Jun 2017)

ED: Publish subject to technical corrections (29 Aug 2017) by Gerhard Herndl

AR by Michelle Graco on behalf of the Authors (01 Sep 2017) Author's response Manuscript

Short summary

The Peruvian coastal upwelling ecosystem is a natural laboratory to study climatic variability and climate change. We examined the variability in the OMZ in the last decades in connection with the equatorial Pacific strong 1997–1998 El Niño event and the influence of central Pacific El Niño events and enhanced equatorial Kelvin wave activity since 2000. The data reveal two contrasting regimes and a long-term trend corresponding to a deepening of the oxygen-deficient waters and warming.