XCO<sub>2</sub> in an emission hot-spot region: the COCCON Paris campaign 2015

Vogel, Felix R.; Frey, Matthias; Staufer, Johannes; Hase, Frank; Broquet, Grégoire; Xueref-Remy, Irène; Chevallier, Frédéric; Ciais, Philippe; Sha, Mahesh Kumar; Chelin, Pascale; Jeseck, Pascal; Janssen, Christof; Té, Yao; Groß, Jochen; Blumenstock, Thomas; Tu, Qiansi; Orphal, Johannes

doi:https://doi.org/10.5194/acp-19-3271-2019

Articles | Volume 19, issue 5

https://doi.org/10.5194/acp-19-3271-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-19-3271-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 5

Research article

|

13 Mar 2019

Research article |

| 13 Mar 2019

XCO₂ in an emission hot-spot region: the COCCON Paris campaign 2015

Felix R. Vogel, Matthias Frey, Johannes Staufer, Frank Hase, Grégoire Broquet, Irène Xueref-Remy, Frédéric Chevallier, Philippe Ciais, Mahesh Kumar Sha, Pascale Chelin, Pascal Jeseck, Christof Janssen, Yao Té, Jochen Groß, Thomas Blumenstock, Qiansi Tu, and Johannes Orphal

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Final revised paper (published on 13 Mar 2019)
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Preprint (discussion started on 25 Jul 2018)

Interactive discussion

Status: closed

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

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RC1: 'Review', Anonymous Referee #1, 19 Aug 2018
- AC1: 'Reply to reviewer #1', Felix Vogel, 02 Jan 2019
RC2: 'Referee Comment on: XCO2 in an emission hot-spot region: the COCCON Paris campaign 2015', Anonymous Referee #3, 06 Nov 2018
- AC2: 'Reply to reviewer #3', Felix Vogel, 02 Jan 2019

Peer-review completion

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

AR by Felix Vogel on behalf of the Authors (24 Jan 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (25 Jan 2019) by Ronald Cohen

RR by Anonymous Referee #3 (07 Feb 2019)

Suggestions for revision or reasons for rejection

Referee Comment on: XCO2 in an emission hot-spot region: the COCCON Paris campaign 2015

General Comments

This revision has significantly improved the manuscript. I found a few small typos and had a few minor questions about Figure 9 and the text referring to that figure, see the specific comments below. After these are addressed, I would recommend the manuscript for publication.

Specific Comments

Ln 77: The “12’000” has an apostrophe instead of a comma. However, maybe there just shouldn’t be any punctuation here to make it consistent with the “10000” on the prior line and other instances later in the paper that do not have thousands separators.

Ln 79: “emission” should be “flux”.

Ln 114-115: The word satellites is repeated unnecessarily, and there is a comma after the period at the end of the sentence. It should be: “…which will not be sampled with low-earth orbit satellites. From…”

Ln 139: The acronym “AIRPARIF” should probably be spelled out.

Ln 142: Just a thought…it might be interesting to look at how emissions from airports compare between surface and column-based measurements. Column based measurements could detect emissions aloft during aircraft takeoff & landing, although perhaps the signal would be too small to detect. No changes are needed in the manuscript, it’s just a thought.

Ln 291: In Equation 3 the “s” superscript on CO2_CHIM and CO2_CAMS seems to be in a different place than in the text (see on lines 285 and 294).

Ln 469-489 and Fig 9: I have a few questions about this section and Fig. 9.

The first question is about the direction of the wind in Fig 9. It looks like in Fig 9 that the highest dCO2 are found at 180 degrees and the lowest dCO2 are at 0 degrees, but to my eyes it looks like in Fig 1 that the direction between PIS-RES is ~10 degrees, and MIT-RES is a little higher, maybe ~40 degrees. (I just looked in the supplement and see they are listed as 7 degrees and 37 degrees). Did the authors orient their analysis such that 180 degrees indicates exactly downwind and 0 degrees as exactly upwind? Maybe not…it’s hard to tell given the color scale used since each color block represents 45 degrees (except for green which has two blocks and represents 90 degrees). Maybe my request would be for the authors to use a finer color scale such that every symbol represents 5-10 degrees and has a unique color. It’s not necessary, but it would certainly help out an interested reader to figure out what exactly is going on.

The second comment is that in the text the authors list the slope of the line, but the explanation could be slightly improved. I would suggest that the sentence on 474-475 be reworded to say that the line is between the modeled vs observed gradient between PIS-RES (or MIT-RES). Here is a suggested rewording: “We find that the modelled vs observed dXCO2 of PIS relative to RES generally falls along the 1:1 line with a slope of 1.07+/-0.09 with…”

The third question is that on line 477-478 the authors say that no slope was calculated for wind directions perpendicular to the direction between the sites. However, the colors of the symbols in Fig 9 indicate winds from all directions. Were the slopes of the lines listed in this section calculated with only a subset of the data (I doubt it, but that is what the text means if taken literally)? I think this just needs a slight bit of clarification here.

Lastly, it might be helpful if the authors included the regression line on Fig 9. Maybe make the 1-1 line light grey so its less prominent and show the regression line as a black line?

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RR by Anonymous Referee #1 (08 Feb 2019)

ED: Publish subject to technical corrections (08 Feb 2019) by Ronald Cohen

AR by Felix Vogel on behalf of the Authors (15 Feb 2019) Author's response Manuscript

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Short summary

Providing timely information on greenhouse gas emissions to stakeholders at sub-national scale is an emerging challenge and understanding urban CO₂ levels is one key aspect. This study uses atmospheric observations of total column CO₂ and compares them to numerical simulations to investigate CO₂ levels in the Paris metropolitan area due to natural fluxes and anthropogenic emissions. Our measurements reveal the influence of locally added CO₂, which our model is also able to predict.