Both reviewers acknowledge the value and potential impact of this paper, but they also raised major comments and suggestions on the structure and science of the manuscript. Based on the review comments and the authors’ reply, this manuscript requires a major revision. I therefore invite the authors to submit a revised manuscript which will be sent for another round of review.

The authors have made substantial revisions and improvement of their initial manuscript after the first round of review. During the second round of review, Reviewer 2 still has some constructive comments and recommendations. Minor revision would be needed before the manuscript is accepted for publication. I invite the authors to submit a revised manuscript following the additional comments of Reviewer 2.