Global Atmospheric δ13CH4 and CH4 Trends for 2000–2020 from the Atmospheric Transport Model TM5 Using CH4 from Carbon Tracker Europe–CH4 Inversions
, Aki Tsuruta 1, Leif Backman 1, Sander Houweling 2,3, Arjo Segers 4, Maarten Krol 5,6, Marielle Saunois 7, Benjamin Poulter 8, Zhen Zhang 9, Xin Lan 10, Edward J. Dlugokencky 10, Sylvia Michel 11, James W. C. White 12 and Tuula Aalto 1Round 1
Reviewer 1 Report
This paper is interesting, and can be accept after minor revision
In the acknowledgment section there is a name of Jarosław Necki, who conduct research since years, bu in manuscript I cant find any comparison or comments about his resaerch. It will be worth to add this analysis and some comments...
Other comment is only about equations- it is better for audience to use the formula as it is presented in ref.46. and to not mix it or use R for standard and samples as R, or as the ratio between isotopes.
The last comment is also editorial, it would be better to use index rather than "-", if you use "-" it seems like subtraction of methan from d13C.
There is too many references...(f all of them are necessery- plese to not to change it)
Comments for author File: 
Comments.pdf
Author Response
Thank you for the comments. Please see the point-by-point response attached.
Author Response File: Author Response.pdf
Reviewer 2 Report
Abstract: This study investigates how grouping of the CH4 emissions by 
13C-CH4 isotopic signatures instead of process type affects the estimated CH4 magnitudes and modelled CH4 and 
13C-CH4 trends.Moreover,a global atmospheric transport model simulations were performed with the inversion results and with modified emissions to investigate the atmospheric
13C-CH4 trends with comparison to observations.The experimental results are rich ,However it is not presented clearly and the thinking about the experimental results is not profound.The following are the specific modification suggestions:
1.Label error of ‘2.2.1 TM5’
2.The format and presentation of the table need improvement
3.The horizontal axis of Figure 1 needs to be modified
4.The figures in your paper are a bit blurry. Please consider replacing them with clearer ones.Such as Figure 1
5.The lines in Figure 6, 7, 8, and 9 are too dense, it is recommended to present them separately
6.The conclusion section is more like the results, and it is recommended to increase in-depth consideration of the experimental results
7.Incorrect citation format of literature
8.There is an issue with the formatting of the article
9.A closer connection is needed between experimental results and conclusions
10.Your manuscript needs careful editing and particular attention to English grammar, spelling, and sentence structure.
11.The references did not cite the forefront
Comments for author File: Comments.pdf
Your manuscript needs careful editing and particular attention to English grammar, spelling, and sentence structure.
Author Response
Thank you for the comments. Please see the point-by-point response attached.
Author Response File: Author Response.pdf
Reviewer 3 Report
In this study, the manuscript challenged the traditional division of emissions and instead group the emissions based on their isotopic signatures and origin. And it categorised the emissions based on their isotopic signatures: fossil-based with more enriched in 13CH4, and biogenic with depleted 13CH4. An effective way to optimise emissions in atmospheric inversions was proposed by the the role of fossil emissions in the global methane budget and that grouping sources isotopically. I think the method used in the manuscript was right, and the result was credible.
English Language is difficult to understand, the authors should make it more easy to read for the readers.
Author Response
Thank you for the comments. Please see the point-by-point response attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Still I dont understand why authors dont want to add any information about works done in Poland by Necki et al.
