Dear Authors,
We have now received the comments of two reviewers and your responses to these comments. As pointed out by the reviewers, there are several issues that need to be addressed before considering the paper for publication. You need to provide a better motivation for the analysis. The methodology used needs to be clarified (please include an improved rationale to address concerns of both reviewers but particularly of reviewer #2), and the discussion needs to be improved by also addressing the issues raised by both reviewers.
Please note that the manuscript will required further assessment by the referees.

We have now received useful comments from two referees. Based on my own careful assessment of the revised paper and the response letter, I agree with the reviewers that there are still some aspects that need to be addressed before this manuscript can be considered for publication.
Though the authors have provided detailed responses to the referee comments, the manuscript will be further improved by integrating some of the material of these responses into a revised submission.

In particular, the revised manuscript could be improved by addressing some of the concerns of the referees:

1) Please include a more clear justification of the methodology emphasizing its appropriateness and its advantages over using a simpler methodology (this will address one of the concerns of reviewer #2, but please note that lack of clarity was also pointed out by the comments reviewer #1 on the original submission).

2) Please analyze/discuss the robustness of results as suggested by reviewer #2, or alternative possible limitations of the study.

3) Regarding the linearity assumption made in Figures 4-6. It would be good to add a very short discussion (a couple of sentences) similar to that included in the authors response, to clearly state that the intent is not to suggest that the points in the figures follow a linear trend.

Though these are some of the main concerns that need to be addressed, please note that it is important to address all the reviewers’ comments as this will help improve the contribution.

The authors have made a great to effort to address all the reviewers comments. The manuscript has greatly benefitted from the review process, thanks to the great feedback provided by the referees, and is now ready for publication.