Ongoing Decline in the Atmospheric COS Seasonal Cycle Amplitude over Western Europe: Implications for Surface Fluxes
, Marine Remaud, Camille Abadie, Fabienne Maignan, Michel Ramonet and Philippe PeylinRound 1
Reviewer 1 Report
This is a very interesting paper, well prepared and well presented. A great Job! Thanks, authors. I only have a minor suggestion for figure 2a. Please clearly present how to get the spring maximum, the autumn minimum (red dots) and the long-term trend (the orange curve). From the caption explanation, it seems the authors used the night time observations to obtain these information. Please explain the reason. Thanks.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
While the topic is good and the analysis is well-done, the importance of the research needs to be better explained.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The research paper is interesting and the methods are appropriate and also important in the climate mitigation studies which focus on the COS concentration anomalies over a European station influenced by multiple sources.
But the manuscript lacks continuity in the methods section could improve the results/conclusion sections with more explanations and can be considered for a major revision. I recommend this article be published in 'Atmosphere ' only after implementing these suggestions.
Comments:
1) Line 65-66: Is the term 'almost invariant ' apt for representing a change in the COS-to-CO2 ratio of 1.22 to 1.23. It would be better to change it in quantitative terms.
2)Line 96-98: This sentence on airmass doesn't seem to fit in this section. Better to move it to the sentence while explaining the results. Continuity is lost here. If the author's intention was to introduce the method of LSMz here, then give a proper short sentence about the transport model here.
3) line107-109: Here also, giving a short explanation of LMDz simulations (which can be made together with comment 2 given above ) will be nice. (I understand that the reference to the paper 17 is given but for continuity for the readers it would be better to give a short sentence before introducing these model names)
4) Lines 124-132: Is it the introduction to LMDz which is mentioned above? Then rearrange the whole methodology part appropriately.
5) Line 134: give Figure 2A instead of Figure 2. B and C are not given in this sentence.
6) Explain how Figure 4 is made. Explain if it is absolute or the difference w.r.t mean. If the authors are stating that there is a decreasing trend from 2016 due to reduced anthropogenic emissions and 1986-2012 is highly correlated with anthropogenic, then what is the status between 2012-2016 and whether taking the mean from 2012-2018 in Figure 4 is accurate?
7) The conclusion can be made more clear. Are you implying towards a more accurate model simulation to represent marine and anthropogenic components? So the decreasing trend which is observed is due to plant uptake or lowering anthropogenic emissions. The lowering of anthropogenic emissions from 2019 is understandable due to the worldwide lockdown. But the reduction is there since 2016. Is there an explanation for this from your studies or pointing towards more understanding
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The authors have addressed the queries properly and revised the manuscript acknowledging the comments and suggestions. A quality check regarding the language and usage is also done.
I recommend this manuscript be published in the 'Atmosphere' journal.
