Airborne observation of mixing across the entrainment zone during PARADE 2011

Berkes, Florian; Hoor, Peter; Bozem, Heiko; Kunkel, Daniel; Sprenger, Michael; Henne, Stephan

doi:https://doi.org/10.5194/acp-16-6011-2016

Articles | Volume 16, issue 10

https://doi.org/10.5194/acp-16-6011-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-16-6011-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 16, issue 10

Research article

|

18 May 2016

Research article |

| 18 May 2016

Airborne observation of mixing across the entrainment zone during PARADE 2011

Florian Berkes, Peter Hoor, Heiko Bozem, Daniel Kunkel, Michael Sprenger, and Stephan Henne

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Final revised paper (published on 18 May 2016)
Supplement to the final revised paper
Preprint (discussion started on 27 Oct 2015)

Interactive discussion

Status: closed

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

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- Supplement

RC C8809: 'Review', Anonymous Referee #1, 01 Nov 2015
- AC C12692: 'Reply to Reviewer #1', Florian Berkes, 24 Feb 2016
RC C9681: 'Referee Comment', Anonymous Referee #2, 24 Nov 2015
- AC C12699: 'Reply to Reviewer #2', Florian Berkes, 24 Feb 2016

Peer-review completion

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

AR by Florian Berkes on behalf of the Authors (29 Feb 2016) Author's response

ED: Referee Nomination & Report Request started (13 Mar 2016) by Graham Feingold

RR by Anonymous Referee #1 (17 Mar 2016)

Suggestions for revision or reasons for rejection

I believe that the revised version has improved, but I found the responses and the subsequent modifications introduced in the revised version still a bit qualitative and not very elaborated. I believe the authors have a complete data set that it is interesting for the reader of ACP, but they do not fully exploit it with a more thorough analysis.

As mentioned in my first revision, it will be very interesting to quantify some of the terms, in particular the role of clouds and entrainment in the mixing and transport of O3 and CO2. I believe this can reinforce the measurements interpretation. I realize that this can be “rough” first-order estimations, in absence to a more complete model study, but I consider that these estimations are an adding value to the paper. Below, I include some specific suggestions.
Taking Equation 5 from Ouwersloot et al. (2013) or Eq.4 at Karl et al. (2007, Journal of Geophysical Research-Atmosphere) as a guidance, and applying it for CO2 and O3 budgets, the entrainment flux for ozone and carbon dioxide can be roughly estimated from the data by combing information of the boundary layer growth presented at Figure 6 with the specific characteristics of CO2 and O3 (figures 7 and 8). This vale of the entrainment flux for ozone can be then compared with an estimation of the deposition flux calculated using the surface measurements of ozone and a characteristic deposition velocity. Similarly, one can obtain a first guess of the contribution of the mass flux that mixes CO2 and O3 from the boundary layer into the free troposphere. In doing so, they could provide some quantification to the new statements regarding the role of clouds and the mass flux (4th paragraph page 17) and the magnitude of entrainment (6th paragraph page 18).

I also found that the authors need to elaborate further on the role of subsidence or other large-scale forcing. By looking to the new figure 6, there is a large decrease in the mixed-layer at 6 UTC (almost 21000 as shown at Figure 7) to less than 1500 m at 10 UTC. I believe that this dynamic behaviour can only be explained by large scale forcing, either of synoptic or mesoscale character. Could the authors describe in a more elaborate manner this behaviour and placed in context for the O3 ad CO2 transport? Could they relate it to section 2.5?

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ED: Reconsider after major revisions (17 Mar 2016) by Graham Feingold

AR by Florian Berkes on behalf of the Authors (13 Apr 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (30 Apr 2016) by Graham Feingold

RR by Anonymous Referee #1 (01 May 2016)

ED: Publish as is (01 May 2016) by Graham Feingold

AR by Florian Berkes on behalf of the Authors (03 May 2016) Manuscript

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Short summary

We presented airborne measurements of CO₂ and O₃ across the entrainment zone over a semi-remote environment in southwestern Germany in late summer 2011 . For the first time CO₂ and O₃ were used as tracer to identify mixing through this transport barrier. We demonstrated that the tracer--tracer correlation of CO₂ and O₃ is a powerful tool to identify entrainment and mixing.