Cross Reference of GDP Decrease with Nighttime Light Data via Remote Sensing Diagnosis
Round 1
Reviewer 1 Report
Below are some major issues with the paper.
1. The objective and the results are not coherent.
2. The methodology based on ArcGis needs to be explained in more detail.
3. The authors are still confused about what is considered a figure or a table.
4. The authors are still confused about the concept of linear regression and linear correlation.
Author Response
Please see attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The years studied should appear in the abstract.
It appeared outside the methodology when the study was carried out.
Please explain it better because your study can improve and contribute scientifically in this field, as there are many studies already carried out.
The tables and graphs are too large and should follow the journal format.
Indeed, the results are inconclusive, but there needs to be a proposal from the authors with well-founded studies to include, together with NTL, other variables that make up an indicator to predict the future better.
The limitations of their study could be improved, as well as a better proposal for future lines of research.
It is recommended to indicate the program used for the statistical analyses. We recommend including a map with the three more relevant areas: USA, Europe, and China.
Conclusions
The conclusions are adequate but need more effort. It is recommended to include a general analysis of the area dealt with, the main results achieved, and the contribution made to the literature, indicating whether the results literature, showing whether the results are consistent with previous literature or, on the contrary, the analysis of specific aspects should be deepened. It is also recommended to include the main lines of future research that would improve the study (in coherence with the section Limitations and future research).
Author Response
Please see attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
This study first uses nighttime light data in a cross-reference with GDP data during instances of global GDP shrinkage. Subsequently, linear regression is used to model yearly average nighttime light and GDP. Overall, the structure of current manuscript is clear. The main issue is that large-scale nighttime light data were averaged, and thus some factors are not considered. To make the conclusion more reliable, there are some major concerns that should be carefully addressed.
(1) Cloud cover changes with time and space. Yearly/monthly variations in cloud cover should be discussed since yearly nighttime light product is used in this study. For example, if global cloud cover in 2011 significantly increased compared to 2010, the average nighttime light data may also decrease. Thus, the impact of global cloud cover on the results should be investigated.
(2) For nighttime light data, there is a saturation problem. How to deal with this issue in this study? Saturation effect may change with time and space, and it will influence the results and conclusion.
Author Response
Please see attachment
Author Response File: Author Response.pdf
Reviewer 4 Report
It is good topic to know socio-economic issue using earth observation data, especially night light data. However, I have several suggestion and question to refine your important paper as follow:
(1) Relation between night light and GDP
In your paper, you only mention positive relationship between 2009 and 2015 about decreasing GDP. How about 2011? Night light is lower than 2010 and 2012 but GDP is growing from 2010 to 2011 and 2012. And also, it seems that value change of night light mean is not same ratio as value change of GDP.
(2) Night light in World, regional, country and province
Only in discussion, you mention about country level GDP. In general, there are many papers about the relationship between economic condition in country and night light. It is better to compare between the previous study and your proposed result.
Author Response
Please see attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Many thanks to the authors for the new manuscript, which reflects the suggestions for improving the work presented.
Congratulations. Kind regards.
Author Response
Thank you very much for your helpful comments and kind words.
Reviewer 3 Report
I have no further comments and suggestions.
Author Response
Thank you very much for your helpful comments in improving the manuscript.
Reviewer 4 Report
Author already mentioned the limitation of this paper but there is no description of way forward in discussion or/and conculsion. It is better to mention more clearly further study topic and content.
Author Response
Thank you for your feedback regarding future research directions. We have revised the manuscript to include this point both in the discussion and conclusion sections, where the topic is briefly introduced at the end of the discussion section, then described in more detail in the conclusion section, including directions such as reducing the spatial scale, using other NTL data products, and studying NTL in correlation with other economic indices' negative growth periods.
