Distribution of suspended particulate matter at the equatorial transect in the Atlantic Ocean

Sivkov, Vadim; Bubnova, Ekaterina

doi:https://doi.org/10.5194/os-17-1421-2021

Articles | Volume 17, issue 5

https://doi.org/10.5194/os-17-1421-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/os-17-1421-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 17, issue 5

Research article

|

21 Oct 2021

Research article |

| 21 Oct 2021

Distribution of suspended particulate matter at the equatorial transect in the Atlantic Ocean

Vadim Sivkov and Ekaterina Bubnova

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Final revised paper (published on 21 Oct 2021)
Supplement to the final revised paper
Preprint (discussion started on 09 Jun 2021)
Supplement to the preprint

Interactive discussion

Status: closed

RC1:
'Comment on os-2021-45', I. Nicholas McCave, 23 Jul 2021

Review of Sivkov, V. And Bubnova, E., “Distribution of suspended particulate matter at the equatorial transect in the Atlantic Ocean”submitted to .

This interesting paper relies on a rare type of dataset, namely measurements of suspended particulate matter (SPM) volume by Coulter counter. It is based on a transect from about 10° north (E) to about 4° North (W) where 61 stations were occupied and 407 samples processed. This quasi synoptic view of the SPM distribution across the equatorial Atlantic reveals several features that are expected, namely high concentrations under the deep Western boundary currents, and one that is not. This is the presence of a column of high suspended sediment concentration over the Sierra Leone rise with a mid-depth maximum between about 1000 and 2000 m. There is a high concentration zone across much of the transect at around 1600 m which is at the same level as a CFC 11 anomaly displayed WOCE line A06, a correspondence that bears further investigation. There are numerous minor infelicities of English usage which I will be happy to transmit to the authors. More detailed comments follow below.

14-21: In the introduction the authors mention the seminal work of Biscaye and Eittreim (1977) who ascribed thick bottom nepheloid layers (BNLs) to upward mixing of SPM, but they should also mention the lateral transfer arguments of Armi (1978) and McCave (1983), the ‘separated mixed layer’ model.

52-56: With so few regional measurements of particle volume by Coulter counter one might ask whether the data presented here are ‘correct’, i.e. whether contamination has been avoided. There is one other large-scale dataset which contains comparable values to those presented here, namely that of McCave (1983). The size range measured in the present study differs slightly from that of McCave but the range here extends somewhat further into the finest sizes at the expense of a cut-off of 20.7 mm versus 32 mm in McCave’s data. So a strict comparison cannot be made. In that paper measurements of both particle volume and concentration by weight were presented and an apparent suspended particle density range was derived with values of 1.65 to 2.23 mg/mm³. The present authors’ ppm are cubic millimetres per litre. With values in the range of 0.01 to 0.08 ppm below the higher concentration surface layer the implied concentrations by weight are about 16 to 180 mg/L, in excellent accordance with suspended matter concentrations measured around the world, e.g.Brewer et al (1976) and the important synthesis of Gardner et al. (2018).

174-184: The authors point to an influence of Amazon River sediments being more important than concentrations at the African end of the transect. Nevertheless there is a marked high at the African end centred on about 800 m that the authors do not discuss and one wonders whether both might be due to internal wave activity on the upper slope.

225 et seq. The authors describe the high mid water concentrations extending down to the bottom over the Sierra Leone rise to the occurrence of aggregates ballasted with Aeolian dust. The concentration zone occurs 1000 km from the coast which is well beyond the zone of coastal upwelling-driven high productivity but does fall in the region of Sahara and Sahelian dust. The authors observe that this column of high concentration occurs under the Guinea dome, a permanent thermal upwelling dome with a cyclonic associated circulation. Other examples of high concentration columns are shown by Biscaye and Eitttreim over Bermuda rise and in the Argentine basin. It seems more likely that the authors observations are related to this circulation feature.

286-291: The intermediate nepheloid layer (INL) downstream of the ‘dam’is similar to the INL demonstrated by Tucholke and Eittreim (1974) deep western boundary current flows over the Puerto Rico Trench.

301-306: Lavelle (2012) has shown the effect of midocean ridges on accelerating currents along their flanks, currents which are likely to then lead to resuspension and generation of nepheloid layers.

310-346. It would be helpful to have a figure in which some of the size distributions were illustrated - cumulative number plots for example.

330-333: it is not clear how a large Brunt-Vaisala frequency in itself would lead to smoothing of a particle size distribution, but perhaps the authors wish to imply that there might be breaking internal wave-driven turbulence associated with frequency maxima that would promote aggregation.

Nick McCave

References (additional to those in the paper).

Armi, L., 1978. Mixing in the deep ocean – the importance of boundaries. Oceanus, 21(1), 14–19.

Brewer, P.G., Spencer, D.W., Biscaye, P.E., Hanley, A., Sachs, P.S., Smith, C.L., Kadar, S., Fredericks, J., 1976. The distribution of particulate matter in the Atlantic Ocean. Earth Planet. Sci. Lett., 32, 393–402.

Lavelle, J. W. (2012), On the dynamics of current jets trapped to the flanks of mid-ocean ridges, J. Geophys. Res., 117, C07002, doi:10.1029/2011JC007627.

Tucholke, B.E. & S.L. Eittreim, 1974. The western boundary undercurrent as a turbidity maximum over the Puerto Rico Trench. J. geophys. Res. 79, 4115-4118.

Citation: https://doi.org/10.5194/os-2021-45-RC1
- AC1: 'Reply on RC1', Ekaterina Bubnova, 03 Aug 2021
  
  Dear Professor McCave
  Firstly, we would like to thank you again for your valuable comments, additional references, and help with English.
  Secondly, we would like to answer every issue.
  
  14-21:
  (1) In the introduction the authors mention the seminal work of Biscaye and Eittreim (1977) who ascribed thick bottom nepheloid layers (BNLs) to upward mixing of SPM, but they should also mention the lateral transfer arguments of Armi (1978) and McCave (1983), the ‘separated mixed layer’ model.
  (2) We added both references
  (3) The works of Armi (1978) and McCave (1983) pointed out the lateral advection of SPM, which occurs due to detaching of bottom mixed layer from the slope and leads to thickening and layering of BNLs.
  
  52-56:
  (1) With so few regional measurements of particle volume by Coulter counter one might ask whether the data presented here are ‘correct’, i.e. whether contamination has been avoided…
  (2) After applying the apparent densities of suspended particles from the (McCave, 1983), we obtained the estimated weight SPM concentrations at the Ioffe-2000 transect. The according changes were put at the beginning of the Results Chapter.
  (3) The work of McCave (1983) contains both the partly comparable dataset of SPM volume concentrations with a slightly wider size range (1.26—32 µm), and the apparent particle densities, that lies between 1.65 and 2.23 mg mm-3. Applying these apparent densities to our volume SPM concentrations, we got the implied weight concentrations about 0.016 to 0.35 mg L-1 (up to 0.8 mg L-1 in exceptional circumstances), which agrees with Brewer et al (1976) and Gardner et al. (2018).
  
  174-184:
  (1) The authors point to an influence of Amazon River sediments being more important than concentrations at the African end of the transect. Nevertheless, there is a marked high at the African end centred on about 800 m that the authors do not discuss and one wonders whether both might be due to internal wave activity on the upper slope.
  (2) We added the lacking discussion
  (3) The Ioffe-2000 transect did not reach the SPM-rich shelf waters, yet the coastal SPM source has caused a local SPM maximum at the margins of the transect at a depth of 300–900 m (up to 0.18 ppm in the west and up to 0.09 ppm in the east). It was the Amazon River that caused the more pronounced rise in SPM concentration at the western edge of transect. It is well known that the surface SPM transport from the Amazon River to the open ocean turns to the northeast alongside the coast (Gibbs, 1974). The eastern edge of the Ioffe-2000 transect is located above the gentle slope between 200 m and 2000 m named Guinea Marginal Plateau (Egloff, 1972), adjacent to the high productive Guinea shelf (Vladimirov et al., 1990; Burlakova et al., 1997). Strong currents (Mittelstaedt, 1991; Stramma et al., 2005, 2008) and implied internal wave activity, based on significant density gradients on the shelf (0–200 m) (Sarafanov et al., 2007), may provide a framework for the SPM lateral transport from the shelf along the gentle Plateau slope.
  
  225 et seq:
  (1) The authors describe the high mid water concentrations extending down to the bottom over the Sierra Leone rise to the occurrence of aggregates ballasted with Aeolian dust. The concentration zone occurs 1000 km from the coast which is well beyond the zone of coastal upwelling-driven high productivity but does fall in the region of Sahara and Sahelian dust. The authors observe that this column of high concentration occurs under the Guinea dome, a permanent thermal upwelling dome with a cyclonic associated circulation. Other examples of high concentration columns are shown by Biscaye and Eitttreim over Bermuda rise and in the Argentine basin. It seems more likely that the authors observations are related to this circulation feature.
  (2) According to Sarafanov et al. (2007), the Guinea Dome cyclonic circulation within the Ioffe-2000 transect was only noticeable within the upper 300 m of the water column, so we believe that it was incomparable with the DWBC that caused the high SPM concentrations shown by Biscaye and Eittreim over Bermuda rise and in the Argentine Basin. Naturally, the circulation in the area of our observations matters, yet we suppose that the entire system of currents, including the Guinea Dome, North Equatorial Current/Countercurrent/Undercurrent and the Canary Current plays a role mostly in the SPM transport from the highly productive area of the Northwest African coast and the region of Sahara and Sahelian dust.
  (3) -
  
  286-291:
  (1) The intermediate nepheloid layer (INL) downstream of the ‘dam’is similar to the INL demonstrated by Tucholke and Eittreim (1974) deep western boundary current flows over the Puerto Rico Trench.
  (2) We did put the additional reference in our paper.
  (3) One of the most notable similar nephelometric features was described for the Puerto Rico Trench near the Navidad sill (Tucholke and Eittreim, 1974).
  
  301-306:
  (1) Lavelle (2012) has shown the effect of midocean ridges on accelerating currents along their flanks, currents which are likely to then lead to resuspension and generation of nepheloid layers.
  (2) We added Lavelle (2012) in our paper.
  (3) High levels of the SPM concentration were also noted above the MAR. There is the northward recirculation of rich in the SPM NADW (Sarafanov et al., 2007), which was noted both sides of the MAR at 36–40° W and 29–32° W. Another type of currents in the area is tidal currents Morozov (2018). According to Lavelle (2012), both these currents may be accelerated along the flanks of the ridge and represent a significant stirring mechanism for abyssal flow and cause the SPM concentration rise. Moreover, the axial region of the MAR including the rift zone experiences high seismicity and bears a large number of earthquake epicenters as well as the sulfide mineralization zones of various origins and bedrock zones showing strong hydrothermal imprints (Mazarovich and Sokolov, 2002); in particular in the Sierra Leone fracture zone, i.e. immediately below the Ioffe-2000 transect (see Fig. 1). Both high seismicity and strong hydrothermal activity may also be able to cause increased SPM concentrations in the bottom layer.
  
  310-346:
  (1) It would be helpful to have a figure in which some of the size distributions were illustrated - cumulative number plots for example.
  (2) We thought that the most typical volume-size SPM distributions will be sufficient, but we will add the cumulative number figure as well.
  (3) Additional Figure 7.
  
  330-333:
  (1) It is not clear how a large Brunt-Vaisala frequency in itself would lead to smoothing of a particle size distribution, but perhaps the authors wish to imply that there might be breaking internal wave-driven turbulence associated with frequency maxima that would promote aggregation.
  (2) We paraphrased the paragraph in order to remove uncertainties.
  (3) Increased shear in pycnoclines and internal wave-driven turbulence would promote aggregation and lead to a further smoothing of the size distribution (equivalent to a cumulative particle number distribution with a slope of -3) of SPM (McCave, 1984).
  
  Additional references
  Burlakova, Z. P., Eremeeva, L. V., & Morozova, A. L. (1997). Suspended matter in the estuaries of the Guinean shelf. physical Oceanography, 8(4), 269-283.
  Stramma, L., Brandt, P., Schafstall, J., Schott, F., Fischer, J., & Körtzinger, A. (2008). Oxygen minimum zone in the North Atlantic south and east of the Cape Verde Islands. Journal of Geophysical Research: Oceans, 113(C4).
  Vladimirov, V. L., Bezborodov, A. A., Martynov, O. V., Ovsyanyi, E. I., & Diallo, B. (1990). Relation between the depth of visibility of a white disk and the concentration of suspended matter in shelf waters off the Republic of Guinea. Soviet journal of physical oceanography, 1(6), 469-474.
  
  Citation: https://doi.org/10.5194/os-2021-45-AC1
RC2:
'Comment on os-2021-45', Anonymous Referee #2, 03 Aug 2021
This MS is a nice presentation of the data collected during one expedition supplemented with literature review. The Coulter counter data is a big plus. My recommendation will be to publish this MS after minor review, addressing few technical issues listed below.

General remark – I am not a native English speaker myself, but I can feel that some parts of the text might benefit from re-wording/re-writing some sentences, which sometimes reads as direct translation from Russian (see for example lines 213-214, etc.).

Fig. 2:

A) It would be useful to add the approximate depth to the 1/2/3 notations, i.e. (numbers are just for illustration – please use the real ones): 1-surface currents (0-100m), 2-subsurface currents (100-300m), 3-deep surface currents (300-500m)

A) and B): looks like isobaths are not at every 500m as stated in the caption. I see 1000, 2000, 3000, 4000, 4500, 5000. Please correct either capture or plots.

Lines 95-100: the sentence “The main existence conditions for GD existence is a cyclonic circulation composed of the eastward NECC and NEUC along with the westward NEC (Stramma and Schott, 1999).”

could use some editing to eliminate a repetition of word “existence”

Fig. 3: search radii? Show the mixed layer depth?

Lines 179-180: use station # for better location reference?

Line 195 – typo ‘occered’

Line 197: “So the local SPM maximum in the GD area within the Ioffe-2000 transect correlate with this data” - show the correlation

Line 255 – typo ‘incresed’

Line 280 – typo ‘depthe’

Line 290 – typo ‘creatint’

Line 336 – typo ‘sized’

Line 363 – typo ‘incresed’
Citation: https://doi.org/10.5194/os-2021-45-RC2
- AC2: 'Reply on RC2', Ekaterina Bubnova, 06 Aug 2021
  
  Dear Referee!
  First of all, we would like to thank you for your time and work with our paper.
  Secondly, we would like to answer all your comments.
  
  General remark
  (1) I am not a native English speaker myself, but I can feel that some parts of the text might benefit from re-wording/re-writing some sentences, which sometimes reads as direct translation from Russian (see for example lines 213-214, etc.).
  (2) We understand that our text is far from perfect in a matter of English. Gladly for us, Professor Ian Nicholas McCave agreed on helping us in this regard, so it will get better.
  
  Fig. 2:
  (1) A) It would be useful to add the approximate depth to the 1/2/3 notations, i.e. (numbers are just for illustration – please use the real ones): 1-surface currents (0-100m), 2-subsurface currents (100-300m), 3-deep surface currents (300-500m) A) and B): looks like isobaths are not at every 500m as stated in the caption. I see 1000, 2000, 3000, 4000, 4500, 5000. Please correct either capture or plots.
  (2) We have changed both the caption of Figure 2 and Figure 2A itself.
  (3)
  
  Figure 2. Generalized circulation schematics within the study area: surface and subsurface layers (A) and intermediate, deep, and bottom layers (B), where 1 — surface currents (from 0 up to 100 m), 2 — subsurface currents (from 100 up to 500 m), 3 — joint surface and subsurface currents (from 0 up to 500 m), 4 — the Deep Western Boundary Current (DWBC) cores, 5 — schematic DWBC recirculation, 6— AABW. The references and current abbreviations are explained in the text. White circles — Ioffe-2000 transect stations.
  
  Lines 95-100:
  (1) The sentence “The main existence conditions for GD existence is a cyclonic circulation composed of the eastward NECC and NEUC along with the westward NEC (Stramma and Schott, 1999).” could use some editing to eliminate a repetition of word “existence”.
  (2) Corrected
  (3) The main existence conditions for GD are a cyclonic circulation composed of the eastward NECC and NEUC along with the westward NEC (Stramma and Schott, 1999).
  
  Fig. 3:
  (1) Search radii? Show the mixed layer depth?
  (2) We are afraid that showing the thin (100 m and less according to Sarafanov et al. (2007) upper mixed layer will not be illustrative, taking into account the fact that the overall depth in Figure 3 is 5000 m. Some information regarding gridding was added to the Figure 3 caption.
  (3) The interpolation was done in the Ocean Data View software (Schlitzer, 2018) and the DIVA gridding (Barth et al., 2010) with 25 permille X-scale length and 65 permille Y-scale length.
  Additional references
  Barth, A., Alvera-Azcárate, A., Troupin, C., Ouberdous, M., & Beckers, J. M. (2010). A web interface for griding arbitrarily distributed in situ data based on Data-Interpolating Variational Analysis (DIVA). Advances in Geosciences, 28, 29-37.
  
  Lines 179-180
  (1) Use station # for better location reference?
  (2) We have corrected the paper.
  (3) The SMP concentrations within the NBC are relatively low (stations AI-910–AI-912).
  
  Line 197:
  (1) “So the local SPM maximum in the GD area within the Ioffe-2000 transect correlate with this data” - show the correlation.
  (2) The mathematical term “correlation” was a wrong choice for this sentence because there was no mathematical comparison.
  (3) The local SPM maximum below the GD area within the Ioffe-2000 transect agrees with this data.
  
  Citation: https://doi.org/10.5194/os-2021-45-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Ekaterina Bubnova on behalf of the Authors (22 Aug 2021) Author's response Author's tracked changes Manuscript

ED: Publish subject to minor revisions (review by editor) (13 Sep 2021) by Mario Hoppema

Dear Drs Sivkov and Bubnova,

Your response to the referees is satisfactory. I went through the revised manuscript and listed my comments below. Please account for those in your final revision, which is close before acceptance.

List of comments:

A lot of abbreviations of water masses, currents and features occur in the manuscript. This makes it sometimes hard to read. I suggest that you use less abbreviations, and/or you present an additional table with all used abbreviations for easy look up.

There exists another paper, Bubnova et al (2020), with a title that suggests to contain data in the same region, and possibly from the same cruise. I cannot read the paper as it is in Russian. I encourage the authors to discuss this paper more extensively, for example in the Introduction or elsewhere, where in particular it should be explained how that paper and the present one differ or complement each other.

L1-2 „A studied oceanographic transect across the Equatorial Atlantic is considered as “screenshot” of suspended particulate matter distribution against a hydrographical background.” Why not just introduce the abstract with the fact that you measured SPM on a transect in the year 2000?

L3 “from top to bottom” I think you mean: in the entire water column
L5 “This process is located within the Northwest African upwelling area” I suggest: This occurs within the Northwest African upwelling area …

L5-7 “This process is located within the Northwest African upwelling area, since the plankton exposed to the Saharan dust abundance form a significant number of aggregates recently transported equatorward via Canary Current.” I do not understand the connection between the first part and the second part of this sentence. Please make clear and modify wording.

L10-11 “The grain size of particles has a polymodal distribution with 2–4 μm and 8–13 μm modes.” It that only for the AABW or for all particles? Please make clear.

L11-12 Idem ditto
L14-15 delete: due to the fact of its importance (this is trivial)

L16 delete: Therefore,
L23 GEOSECS is Geochemical Ocean Sections Study

L23 an early GLOBAL description of …
L25 … in Brewer et al. (1976) at … (format) Please also check at other places in the manuscript.

L29 This does not need to be in parentheses.
L42 … have been published in far less detail …

L42-43 “due to the fact that not all the peculiarities were in accordance with general knowledge” This sentence makes the reader curious. Please give some example of this.

L43-44 “So far, the ideas have been formed to explain the features of the SPM distribution obtained on the transect.” It is not clear to me what this sentence wants to convey. Please modify.

L47 “8th cruise of the R/V Akademik Ioffe” Is there any more info on this cruise that can be cited? Cruise report or report/publication in which the cruise is described?

L48 “just before the start of the main transect” instead of “just before the transect conduction”

L49 Please define “Ioffe-2000” in the previous sentence
L49 “the hydrological complex” This is not a common expression. Do you mean the CTD with rosette sampler? Please explain and modify

L58 Salinity is dimensionless, psu should not be used. Please indicate whether salinity was measured on the practical salinity scale.

Section 2 Please give the precision and accuracy of SPM concentration. Please add the size of the samples for determining SPM concentration.

L110 define NICC
L123 “The maximum of one of the CFCs (F11 — trichlorofluoromethane) represents LNADW” This is not quite clear. I suggest something like: The highest values of one of these CFCs (F11 — trichlorofluoromethane) are found in the LNADW.

L130 through (typo)
L131 “(water with °4 > 45.90 kg m-3)” This is not clear. Do you mean water with temperature of 4°C?

L132 “The AABW consists of old deep-water masses (Reid, 1994) with negligible F11 concentrations” This is a very old reference for such a contention about transient tracers. I could imagine that between 1994 and now the F11 concentration has increased. Please give more recent reference and check the contention. Actually, at L139 you mention the rising F11 in AABW.

L138 (> 0.07 pmol kg-1) (format of hyphen) Hyphen superscript should also be done in concentrations at other places in the text.

Caption of Fig. 3 “1— sampling points, 2 — northward current, 3 — southward current, 4 — eastward current” Because it is not clear what the numbers stand for, I suggest to add in parentheses: (numbers indicated in panel bottom left)

L161 delete “caused by primary production”. One sentence later you explain that not only PP causes this but more factors.

L164 Please add: … accumulation in the surface layer may be the existence of the pycnocline at the bottom of the surface layer, which slows the sedimentation …

L165 I suggest: “The “sedimentation barrier” can be seen as a visible pycnocline …
L169 calcium carbonate (CaCO3) … (note subscript for 3)

L174/175 Please show the geographical names used here in the figures (map and possibly section plot)

P8 and 9 The discussion of the SPM results makes frequent use of the hydrographic data. As the hydrographic results are not part of this manuscript, it is for the reader hard to understand. Please add a figure of the hydrography of the IOFFE-2000 section (potential temperature, salinity or density).

L213 “at various mid-depths” I think this is not clear and well-defined. Please modify
L218 “ … so the SPM concentrations were low (0.01–0.03 ppm).” Is this lower than usual in the clear water layer? Please specify

L229-230 “The water exchange in the deep layers of Eastern Atlantic …” What kind of exchange is meant here? Between which water masses?

L236 above the Sierra Leone Rise (Fig. 3) (refer the Fig. 3)
L239 We explain this …

Caption Fig. 5: Please indicate that this is a small deep part with more detail of the main contour plot in Fig. 3

L269-270 “an increase in the SPM concentrations” What increase do you mean? Compared to what? Or do you mean high values? With the one time section of SPM one cannot determine a difference, or increase.

L278-279 verb missing in sentence
L289 I do not understand the notation after AABW. Please explain or modify

L300 Spell out m.a.b.
L308 … were also noted above the MAR – Please refer to figure

L309 change to: of NADW rich in the SPM
L322 “The overall cumulative number distribution for Ioffe-2000 transect …” Is this the mean of all stations of the Ioffe-2000 transect?

L324-325 “The explanation for volume-size distributions was generally based on the results of the HEBBLE project in abyssal waters (the Nova Scotia Rise, 1977–1984)” It is not clear to me what you mean. Please clarify

L328-329 “during the Ioffe-2000 cruise there was a possibility to count the fine part of the coarse mode only” This is not clear, I think you mean: … during the Ioffe-2000 cruise possibly only the fine part of the coarse mode was counted. Please change if needed

L329 elevated instead of increased
L332 “The most representative volume-size distributions in our study are shown in Figure 8.” It is fine to show this figure with typical distributions. However, it does not become clear how many stations have such distributions and how many stations have different ones, i.e., no (semi-)quantitative info is given on the full transect. Would it be possible to give more such information?

L360, 367, 373 Use: First, Second and Third for clarity
L365-366 “Our studies results agree with the fact that higher aggregate numbers and higher sinking velocities may increase the carbon export to deep ocean layers.” Please give more detail where exactly you base this on.

L366-367 “Changes in dust sedimentation may bring about drastic changes in the global ocean due to the boost that trace nutrients from dust may cause for primary production.” I think this does not follow from this work and should be deleted or needs a reference.

L388 delete: 380

References
L399 volume and page numbers missing
L444 editor of book missing
L459 Any more info on the report?
L461 editor of book missing
L467 The second author is called: Rutgers van der Loeff, M.
L475 Full reference: 117, C07002, doi:10.1029/2011JC007627.
L486 pages missing
L521 volume number missing
L541 full reference: 112, C12023, …

Supplement
Please name the table and give a short description what is shown here.

Thanks and best wishes
Mario Hoppema
(editor)

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AR by Ekaterina Bubnova on behalf of the Authors (26 Sep 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (27 Sep 2021) by Mario Hoppema

AR by Ekaterina Bubnova on behalf of the Authors (27 Sep 2021)

Short summary

A suspended particulate matter distribution against a hydrographical background was studied along an oceanographic transect across the Equatorial Atlantic in the year 2000. Alongside the general agreement with the three-layer model of the ocean suspended particulate matter distribution, there was a massive area with high SPM concentrations above the Sierra Leone Rise and local SPM maxima in the bottom layer within Antarctic Bottom Water.