Meteorological factors controlling low-level continental pollutant outflow across a coast

Peake, D. L.; Dacre, H. F.; Methven, J.; Coceal, O.

doi:https://doi.org/10.5194/acp-14-13295-2014

Articles | Volume 14, issue 23

https://doi.org/10.5194/acp-14-13295-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-14-13295-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 23

Research article

|

15 Dec 2014

Research article |

| 15 Dec 2014

Meteorological factors controlling low-level continental pollutant outflow across a coast

D. L. Peake, H. F. Dacre, J. Methven, and O. Coceal

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Final revised paper (published on 15 Dec 2014)
Preprint (discussion started on 30 Apr 2014)

Interactive discussion

Status: closed

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

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RC C2686: 'Anonymous Referee comments', Anonymous Referee #1, 24 May 2014
- AC C5477: 'Authors response to reviewer 1', Helen Dacre, 31 Jul 2014
RC C2921: 'Referee comments', Anonymous Referee #2, 29 May 2014
- AC C5478: 'Authors response to reviewer 2', Helen Dacre, 31 Jul 2014

Peer-review completion

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

AR by Helen Dacre on behalf of the Authors (31 Jul 2014) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Aug 2014) by Geraint Vaughan

RR by Anonymous Referee #1 (12 Aug 2014)

Suggestions for revision or reasons for rejection

Major comments:

Section 2.2 is much improved because it now includes a comparison between the model and the NOAA P3 observations. However, this section is difficult to follow because it mixes new results with those from previous studies and I’m not always sure if the authors are discussing new results or previous studies. To make the section more clear please first discuss the new results, and then discuss how your new results compare to the previous studies.

Line 425
More thought needs to be put into the causes of ozone depletion in the marine boundary layer. The authors claim that ozone is deposited to the ocean surface. Is there a reference for this claim? Ozone is not soluble in water so it can’t be taken up by the body of water. Are you implying that ozone is destroyed by material on the surface of the water? Is there a reference for this?
Similarly it is claimed that ozone precursors become more dilute in an environment with high water vapour. What does water vapour have to do with dilution which is a mechanical mixing process regardless of the composition of the atmosphere? Can’t ozone precursors become diluted just as easily in a dry air mass?

Line 490
Here you discuss the polluted air becoming decoupled from the surface over the ocean forming the coastal outflow layer that your study focuses on. But looking at the measurements in Figure 4 I don’t see a decoupling of a polluted layer from the surface. The pollutants seem uniform in the lowest 1 km of the atmosphere. Therefore I don’t see the need to focus the study of pollutant outflow on the layer above the marine boundary layer. To me it seems more useful to first discuss pollutant outflow as a whole, regardless of layer, but to then also break the outflow into the two layers analyzed in the text.

Minor Comments
If no explanation is given for a comment, please insert the suggested text into the appropriate place in the manuscript.

line 92
which were observed

line 281
it is reasonable to conclude that

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WP-3D

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I’m not sure what is meant by “the most interesting part of parameter space”

line 319
“and is subject to advection”

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need a reference for the claim that the CO lifetime is 25 days

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Far from emission sources it comes into

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So the approach taken here will be to compare over the western North Atlantic Ocean away from strong CO and NOx emissions.

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I’m not sure what is meant by leading order. Do you mean first order?

line 432
this sentence seems to be missing some words.
What is meant by “with the ocean surface and more humid,” ?

Line 435
This comment about air crossing the Atlantic without losing its pollution signature is not really correct. Owen et al. 2006 and Real et al. 2007 show that the pollution becomes diluted and is transformed chemically.

Line 897
to a tracer advection rate

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RR by Anonymous Referee #2 (03 Sep 2014)

ED: Reconsider after minor revisions (Editor review) (08 Sep 2014) by Geraint Vaughan

AR by Helen Dacre on behalf of the Authors (14 Oct 2014) Author's response Manuscript

ED: Publish as is (30 Oct 2014) by Geraint Vaughan

AR by Helen Dacre on behalf of the Authors (06 Nov 2014)