The Importance of Spatial Resolution in the Modeling of Methane Emissions from Natural Wetlands
Round 1
Reviewer 1 Report
In this paper, the authors investigate the impact of model resolution on the simulated wetland methane emission for the Fenno-Scandinavian Peninsula. Obviously, the authors have done a lot of work. However, there are flaws in the paper organization and structure as well as within the methods descriptions. Major critical shortcomings within the paper are 1) the authors simulated spatial patterns of wetland methane emission at different resolutions to assess the uncertainty caused by the wetland area. However, it is evident that calculating the percentage of wetland area in a grid cell can solve this problem. Besides, the method section of this article extensively elaborates on some general knowledge about changing resolution. It is unclear what novel insight could be gained from the results. 2) When estimating the KCH4 value, the authors did not elaborate on the specific parameter calibration method, nor provide reliable validation results, it would be better to calculate some statistics to evaluate model performance. The model calibration using two sample sites is not sufficient to support reliable model simulation of methane emissions from different vegetation types on a large scale. 3) The methane estimated model used in this article contradicts basic knowledge, such as the relationship between soil moisture content and methane emissions is not linear. As the authors mentioned in the article, the methane emission capacity reaches its maximum when the soil moisture content reaches moderate. Therefore, the reliability of this methane emission model is very low. 4) I found that this paper preprints in Biogeosciences, and I am not sure whether it involves the issue of duplicate submission. In a word, I would suggest that it is rejected as this paper is lacking novelty and some deep insights.
Author Response
Dear Reviewer#1,
We would like to express our gratitude for taking the time to review our manuscript and for providing us with valuable feedback. We appreciate your thoughtful comments and suggestions, which have helped us to improve the quality and clarity of our work.
We have carefully considered all of your comments and questions, and have provided detailed responses and explanations in the attached document. We hope that these responses address all of your concerns and provide you with the information you need to evaluate our manuscript.
We understand that the review process is an essential component of the scientific publishing process, and we value the insights and perspectives of our peers. We appreciate the effort and expertise that you have invested in reviewing our manuscript, and we hope that our responses are satisfactory.
Once again, thank you for your time and effort in reviewing our manuscript. We look forward to hearing back from you regarding the suitability of our manuscript for publication in your esteemed journal.
Author Response File: 
Author Response.docx
Reviewer 2 Report
This paper investigates the impact of model resolution on simulated methane emission for the Fenno-Scandinavian Peninsula. This is conducted via the coarsening of a simplified CH4 emission model in several steps, along with a high-resolution wetland map and soil carbon map. The authors find that the CH4 emission is sensitive to the treatment of wetland fraction, the wetland mapping uncertainties, as well as the correlation between soil moisture and soil carbon availabilty.
Overall, this paper well written, the arguments are valid, and the results are clearly presented. I would appreciate if the authors can provide some insights by addressing the comments listed below.
It seems like most of the uncertainty in the estimates of CH4 emission comes from 1. The correlation between SOC and SM, and 2. The SM dataset that was used (ERA5 vs. PCRG), and 3. the wetland map that was used. While you have experimented with different values of SM in the both wetland and upland, it would be interesting to see a separate scenario where the input SOC is different from the ISRIC 2017 dataset, and to also examine the correlation between the input SOC dataset with the SM dataset. The results may support the discussion that the correlation between these two terms determines the resolution dependence.
Also, from Figure 8, it seems like the different wetland extent maps have very large discrepancies amongst themselves. Maybe I am not up to date on the different wetland extent maps, it seems like using different wetland extent maps can introduce very large uncertainty in the modeled CH4 emission, even under the same resolution (at 0.5 degree). Could you comment on how large the uncertainty can be?
I would also think that sub-grid wetland variation could impact the resolution dependence observed in the model outputs. I would appreciate some more details on how this was investigated.
Minor comments:
Line 110-111: (SC) should be (SOC)?
Line 221: incomplete sentence.
Line 226: I thought the SM for upland was 0 for Sn.1 according to Table 1.
Line 242: remove “,” after “and”.
Line 286: difference between the coarser resolution and the reference resolution? I think this sentence is excessive since you describe the same thing in the next sentence.
Line 308 to 310: Please rephrase this sentence. It seems like you are simply testing the impact of a smaller contrasts in SM between wetland/upland.
Line 310: Please point to the figure (Figure A.2) when discussing the results.
Line 337: Sn.4-a?
Line 350 to 351: Please be specific on what he impact is, I.e., CH4 emissions decrease with resolution?
Line 353: change “to” to “the”.
Line 452: (PDFs)
Line 501: Please be consistent in your reference formatting. Follow the MDPI guideline if possible (https://www.mdpi.com/authors/references).
Author Response
Dear Reviewer#2,
We would like to express our gratitude for taking the time to review our manuscript and for providing us with valuable feedback. We appreciate your thoughtful comments and suggestions, which have helped us to improve the quality and clarity of our work.
We have carefully considered all of your comments and questions, and have provided detailed responses and explanations in the attached document. We hope that these responses address all of your concerns and provide you with the information you need to evaluate our manuscript.
We understand that the review process is an essential component of the scientific publishing process, and we value the insights and perspectives of our peers. We appreciate the effort and expertise that you have invested in reviewing our manuscript, and we hope that our responses are satisfactory.
Once again, thank you for your time and effort in reviewing our manuscript. We look forward to hearing back from you regarding the suitability of our manuscript for publication in your esteemed journal.
Author Response File: Author Response.docx
Reviewer 3 Report
Dear Editor and authors,
I read with great interest the manuscript titled: “The importance of spatial resolution in the modelling of methane emissions from natural wetlands”. The manuscript presents a quantification of methane emissions from wetlands in the Fennoscandinavian peninsula using a simplified emission model that considers Soil Organic Carbon, Soil Moisture and the land cover as the main drivers of methane emissions. The authors consider a number of scenarios and satellite derived products in their study and based on different quantifications of emissions, the authors assess the effects that spatial resolution has on the quantification of total emissions. The authors have presented a very good manuscript, it reads very well, it is well structured, with quality figures and clear connection between the sections. I believe the manuscript is adequate for publishing in Remote Sensing.
Before publication, however, I have one recommendation for improving the manuscript. The methods presented by the authors are clear and should be highly reproducible in other regions, however, datasets implemented in this study may not be as readily available in different regions. As part of the final discussion, the authors also comment on the uncertainty of the products used in this work. As part of the discussion, I believe the authors should comment on alternative databases available globally for SOC and SM (if available) with other resolutions that could potentially be implemented inside or outside of their study region. This would, in my opinion, reinforce the message of the manuscript of the necessity for continuing to increase wetland data resolution worldwide as well as provide the manuscript with a more general relevance than the focus on a single site/region.
Author Response
Dear Reviewer#3,
We would like to express our gratitude for taking the time to review our manuscript and for providing us with valuable feedback. We appreciate your thoughtful comments and suggestions, which have helped us to improve the quality and clarity of our work.
We have carefully considered all of your comments and questions, and have provided detailed responses and explanations in the attached document. We hope that these responses address all of your concerns and provide you with the information you need to evaluate our manuscript.
We understand that the review process is an essential component of the scientific publishing process, and we value the insights and perspectives of our peers. We appreciate the effort and expertise that you have invested in reviewing our manuscript, and we hope that our responses are satisfactory.
Once again, thank you for your time and effort in reviewing our manuscript. We look forward to hearing back from you regarding the suitability of our manuscript for publication in your esteemed journal.
Author Response File: Author Response.docx
