Global Nighttime Light Change from 1992 to 2017: Brighter and More Uniform
Round 1
Reviewer 1 Report
This is an interesting manuscript that compares nighttime lighting patterns to economic development and develops models to quantify the relationship. I think the literature review is appropriate and identifies the key issues in the academic literature. The methods flow from the literature review and are appropriate. The models are well developed and explained. The results are clear and appropriate. I had two minor editorial comments. First, check the paper and revise passages written in passive tense. Second, in the abstract (line 15) you introduce the acronym TNL. Please define the acronym at this point, especially since people will read the abstract before deciding to read the article.
Overall, this is a well researched and well written paper. Congratulations on a great project!
Author Response
Thank you very much for your affirmation and appreciation of the subject matter, methods and content of this article. We are willing to further combine satellite remote sensing data resources and spatiotemporal analysis methods with hot topics in economic and social research to attain a faster and more convenient technical solution and provide a different and novel perspective to resolve the current global economic and sociological problems.
In response to the use of the passive tense and acronym definition in the paper, we comprehensively and carefully cross-checked and edited the text, and a professional language editing company was contracted to edit the paper. We sincerely hope that the text has been greatly improved and that the paper meets the language standards of the target journal.
Author Response File: 
Author Response.doc
Reviewer 2 Report
So many abbreviations make the report difficult to read. Check whether abbreviations used only a few times cannot better be replaced by the complete term.
A list with all abbreviations and their meaning at the beginning of the report would make the reading of the report much easier.
Some abbreviations are needless complicated: LNLZ, MNLZ etc. the meaning of the N in this abbreviation is not clear and not needed. I recommend to change these abbreviations into: LBZ, MBZ etc. with the meaning: Low Brightness Zone, Medium Brightness Zone. The word brightness automatically includes Light: no brightness without light (so in this abbreviation the L of Light is not needed if the word Brightness is used).
lines 145 -148: give reason why this is believed.
line 203: typo? "an increase of 1.2 times" must be "an increase of 2.2"
Fig. 3 on a printed PDF version the legend is not readable; what parameter and unit is the legend?
Figure 3 Caption line 216: the red (on my printed PDF the circles are not RED) circle highlights FIVE (instead of six) areas.
line 252 "or the the areas brightening of the light" change into "or the increase of bright areas"
line 266 change "brightening areas" into "bright areas" (brightening areas suggests "areas becoming more bright at this very moment"). Change the term "brightening areas all through the paper into "bright areas" (especially also in Table 1).
line 317 an example where an abreviation is not needed: change "NL" into "night light"
Figure 7 change "Ln" into "log". Ln is the abreviation for the natural logarithm (e). Log is 10 logarithm.
line 360-361: "the number of people" in thousands, millions, billions?
Author Response
Comment 1: So many abbreviations make the report difficult to read. Check whether abbreviations used only a few times cannot better be replaced by the complete term.
A list with all abbreviations and their meaning at the beginning of the report would make the reading of the report much easier.
Some abbreviations are needless complicated: LNLZ, MNLZ etc. the meaning of the N in this abbreviation is not clear and not needed. I recommend to change these abbreviations into: LBZ, MBZ etc. with the meaning: Low Brightness Zone, Medium Brightness Zone. The word brightness automatically includes Light: no brightness without light (so in this abbreviation the L of Light is not needed if the word Brightness is used).
line 317 an example where an abbreviation is not needed: change "NL" into "night light"
Response: Thank you for your suggestion. It did improve the readability. We have listed all uncommon acronyms at the beginning of the paper. We have also modified the definitions and abbreviations of the LBZ, MBZ and HBZ.
Comment 2: lines 145 -148: give reason why this is believed.
Response: We apologize that the original draft did not elaborate on the assertion here. In the newly submitted manuscript, we have provided a further explanation (lines 165-168), i.e., considering that the human economy and various energy consumption sources are generally increasing on a global scale, it is commonly believed that later DN values of nighttime light images should at least be larger than or equal to previous DN values in time series nighttime light datasets [35]. Furthermore, we explain the reliability of this assertion and possible influencing factors in section 4.3, Uncertainty.
Comment 3: line 203: typo? "an increase of 1.2 times" must be "an increase of 2.2"
Response: We wanted to express how many times the global TNL has increased. To avoid ambiguity, we rewrote the entire sentence. Now it appears as "the global TNL in 2017 is 2.2 times that in 1992". We also revised other similar expressions throughout the text.
Furthermore, we contracted a professional language editing company to edit the paper to more clearly convey the authors’ original meaning. We sincerely hope that the newly submitted paper is greatly improved in writing quality and meets the language standards of the target journal.
Comment 4: Fig. 3 on a printed PDF version the legend is not readable; what parameter and unit is the legend? Figure 3 Caption line 216: the red (on my printed PDF the circles are not RED) circle highlights FIVE (instead of six) areas.
Response: We resubmitted the manuscript in .doc format. We hope that the newly generated PDF file is correctly displayed. In Figure 3, the legend shows the slope of the interannual change in the nighttime lights from 1992-2017, and the unit is the digital number per year (DN/Year). We also corrected any errors. There should be 5 black ellipses that highlight the 5 hot zones around the world.
Comment 5: line 252 "or the areas brightening of the light” change into "or the increase of bright areas". line 266 change "brightening areas" into "bright areas” (brightening areas suggests "areas becoming more bright at this very moment"). Change the term "brightening areas all through the paper into "bright areas" (especially also in Table 1).
Response: Thank you for your suggestion. We have revised all similar inaccurate expressions throughout the paper according to your suggestions.
Furthermore, we contracted a professional language editing company to edit the paper to more clearly convey our original meaning. We sincerely hope that the newly submitted paper is greatly improved and meets the language standards of the target journal.
Comment 6: Figure 7 change "Ln" into "log". Ln is the abbreviation for the natural logarithm (e). Log is 10 logarithm. line 360-361: "the number of people" in thousands, millions, billions?
Response: We have modified this scatterplot and the expression of the regression equation according to your suggestions. Please review our latest manuscript. In Figure 7, the unit of the population living in poverty is the number of individuals, and the unit of the LBZ area is square kilometers.
Author Response File: Author Response.doc
Reviewer 3 Report
The engish is far from perfect, to the point of being difficult to understand at some places. Please let the article be checked by a qualified person.
Particular comments:
line 15: define TNL
lines 19-20: I do not understand the sentence, please improve.
line 94, last word: "authors" not "author"!
line 112: define DN
line 124: write the full title for GADM
Figure 1: define NTL
lines 144 and 145: again, "authors" not "author"
line 160: start the sentence with "For the..."
Fig 2, on the image: the spelling of correction is wrong!
lines 167-186: improve language
Results. in what units is TNL epressed? I assume relative, but this should be expalined at the beginning of the section 3.
Figure 3: I see black ellipses, not red circles. Where is #6? I see only 5 of them. Also, line 216, should be "red circles" not "red circle".
lines 240-245: something went wrong here, correct!
line 254: delete "the tree countries"
line 263: increse of 0.52 times. This is decrease, I assume it should be 1.52 so please correct.
Author Response
Comment 1: The English is far from perfect, to the point of being difficult to understand at some places. Please let the article be checked by a qualified person.
Response: We apologize for the language problems in the original manuscript. We have comprehensively and carefully cross-checked and revised the text in the updated manuscript. Furthermore, we have contracted a professional language editing company to edit the paper to more clearly convey our original meaning. We sincerely hope that the newly submitted paper has been greatly improved and meets the language standards of the target journal.
Comment 2:
line 15: define TNL
line 112: define DN
line 124: write the full title for GADM
Figure 1: define NTL
Response: We reviewed all abbreviations and removed any unnecessary abbreviations in the abstract. The authors listed all uncommon acronyms at the beginning of the paper.
All abbreviations, e.g., TNL, DN, GADM, and NTL, were defined upon first occurrence in the text.
Comment 3:
lines 19-20: I do not understand the sentence, please improve.
line 94, last word: "authors" not "author"!
line 160: start the sentence with "For the..."
Fig 2, on the image: the spelling of correction is wrong!
lines 167-186: improve language
lines 144 and 145: again, "authors" not "author"
lines 240-245: something went wrong here, correct!
line 254: delete "the three countries"
Response: We apologize for the spelling and grammatical errors in the last draft. We have rewritten the text. Furthermore, we have contracted a professional language editing company to edit the paper to more clearly convey original meaning. We sincerely hope that the newly submitted paper has been greatly improved and meets the language standards of the target journal.
Comment 4: Results. in what units is TNL expressed? I assume relative, but this should be explained at the beginning of the section 3.
Response: The TNL index is the cumulative sum of the DN values of all pixels in one nighttime light image of an area, and it is defined in section 2.3. Therefore, the TNL index is dimensionless.
Moreover, in Figure 3, the legend shows the slope of the interannual change in the nighttime lights from 1992-2017, and the unit is the digital number per year (DN/Year). We have explained the abovementioned index in the corresponding places in the text.
Comment 5: Figure 3: I see black ellipses, not red circles. Where is #6? I see only 5 of them. Also, line 216, should be "red circles" not "red circle".
Response: Thank you for your careful review. We have corrected any errors. There should be 5 black ellipses that highlight the 5 hot zones around the world.
Comment 6: line 263: increase of 0.52 times. This is decrease, I assume it should be 1.52 so please correct.
Response: Thank you for your careful review. Your assumption is correct. We definitely made a mistake on how to express the temporal relationship. We revised this sentence and other similar expressions throughout the paper.
Author Response File: Author Response.doc
