Identification of topographic features influencing aerosol observations at high altitude stations

Collaud Coen, Martine; Andrews, Elisabeth; Aliaga, Diego; Andrade, Marcos; Angelov, Hristo; Bukowiecki, Nicolas; Ealo, Marina; Fialho, Paulo; Flentje, Harald; Hallar, A. Gannet; Hooda, Rakesh; Kalapov, Ivo; Krejci, Radovan; Lin, Neng-Huei; Marinoni, Angela; Ming, Jing; Nguyen, Nhat Anh; Pandolfi, Marco; Pont, Véronique; Ries, Ludwig; Rodríguez, Sergio; Schauer, Gerhard; Sellegri, Karine; Sharma, Sangeeta; Sun, Junying; Tunved, Peter; Velasquez, Patricio; Ruffieux, Dominique

doi:https://doi.org/10.5194/acp-18-12289-2018

Articles | Volume 18, issue 16

https://doi.org/10.5194/acp-18-12289-2018

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

https://doi.org/10.5194/acp-18-12289-2018

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

Articles | Volume 18, issue 16

Research article

|

24 Aug 2018

Research article |

| 24 Aug 2018

Identification of topographic features influencing aerosol observations at high altitude stations

Martine Collaud Coen, Elisabeth Andrews, Diego Aliaga, Marcos Andrade, Hristo Angelov, Nicolas Bukowiecki, Marina Ealo, Paulo Fialho, Harald Flentje, A. Gannet Hallar, Rakesh Hooda, Ivo Kalapov, Radovan Krejci, Neng-Huei Lin, Angela Marinoni, Jing Ming, Nhat Anh Nguyen, Marco Pandolfi, Véronique Pont, Ludwig Ries, Sergio Rodríguez, Gerhard Schauer, Karine Sellegri, Sangeeta Sharma, Junying Sun, Peter Tunved, Patricio Velasquez, and Dominique Ruffieux

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Final revised paper (published on 24 Aug 2018)
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Interactive discussion

Status: closed

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

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RC1: 'comments', Anonymous Referee #1, 23 Oct 2017
- AC1: 'Answers to the referee's comments', Martine Collaud Coen, 02 Feb 2018
RC2: 'Major revision required', Anonymous Referee #2, 07 Dec 2017
- AC1: 'Answers to the referee's comments', Martine Collaud Coen, 02 Feb 2018

Peer-review completion

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

AR by Anna Mirena Feist-Polner on behalf of the Authors (05 Feb 2018) Author's response

ED: Referee Nomination & Report Request started (27 Feb 2018) by Laurens Ganzeveld

RR by Anonymous Referee #1 (25 Mar 2018)

RR by Anonymous Referee #2 (13 Apr 2018)

ED: Reconsider after major revisions (17 Apr 2018) by Laurens Ganzeveld

AR by Martine Collaud Coen on behalf of the Authors (07 May 2018) Author's response Manuscript

ED: Reconsider after major revisions (17 Jun 2018) by Laurens Ganzeveld

ED: Referee Nomination & Report Request started (18 Jun 2018) by Laurens Ganzeveld

RR by Anonymous Referee #2 (23 Jul 2018)

Suggestions for revision or reasons for rejection

After reading through the authors' replies and the careful comments
by the editor I only have a few additional remarks. Most of the
replies and corrections help to clarify the paper but I think with
a little additional work some more meaningful results could have
been obtained. But I will leave this for future work.

Some remaining concerns:

DBinv: Since the authors are really so insisting on keeping this
parameter in their analysis I suggest at least to change the name
of it throughout the manuscript. Instead of 'drainage basin for
thermally lifted pollutants', which I am still not convinced it
represents, the authors should just stay with 'inverse drainage
basin' and describe it as potentially reflecting the probability for
thermally lifted pollutants to reach the site. Seems to be the same
thing, but it really makes a difference if a confusing name is
given or a topographic parameter is just tested. However, then in the conclusion it should
also be made clear that the parameter was not a good predictor and,
hence, the suggested analogy of inverse drainage flow and flow
barriers did not work so well.

Latitude and thermally induced transport: Sure latitude is a good
predictor. The differential heating that is necessary to produce
thermal lifting obviously depends, among other factors, on
latitude. Why else are the authors focusing on summer for
mid-latitude sites. The absence of strong differential heating is
another factor why the results of ZEP are so poor. There simply is
no thermal lifting.

Regression model: I was thinking about generalised additive models
(GAM, Wood et al., 2006) and parameter selection like in Jackson et
al. (2009). Certainly there is a way to deal with non-normal
distributions if necessary. There are even more advanced methods
coming up in the age of machine learning (random forests, etc.).
But I can see that this goes beyond the scope of the current paper
but it could have significantly improved the paper and removed some of the
speculative aspects.

References

Jackson, L. S., Carslaw, N., Carslaw, D. C., and Emmerson, K. M.:
Modelling trends in OH radical concentrations using generalized
generalized additive models, Atmos. Chem. Phys., 9, 2021–2033,
doi:10.5194/acp-9-2021-2009, 2009.

Wood, S. N.: Generalized Additive Models: An Introduction with R.
Chapman & Hall/CRC. Boca Raton, USA, ISBN 9781584884743, 2006.

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ED: Publish subject to minor revisions (review by editor) (23 Jul 2018) by Laurens Ganzeveld

AR by Martine Collaud Coen on behalf of the Authors (25 Jul 2018) Author's response Manuscript

ED: Publish as is (30 Jul 2018) by Laurens Ganzeveld

AR by Martine Collaud Coen on behalf of the Authors (06 Aug 2018) Author's response Manuscript

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Short summary

High altitude stations are often emphasized as free tropospheric measuring sites but they remain influenced by atmospheric boundary layer. An ABL-TopoIndex is defined from a topography analysis around the stations. This new index allows ranking stations as a function of the ABL influence due to topography or help to choose a new site to sample FT. The ABL-TopoIndex is validated by aerosol optical properties and number concentration measured at 29 high altitude stations of five continents.