Estimating Daily NO2 Ground Level Concentrations Using Sentinel-5P and Ground Sensor Meteorological Measurements
Round 1
Reviewer 1 Report
The paper deals with the relevant problem of air pollution with NO2 in the troposphere of the city of Northern Italy Milan. The study is carried out by using ground meteorological data and Sentinel- 471 5P NO2 observations and applying different models (state-of-the-art Machine Learning models, linear regression models) and feature selection algorithms. This research is relevant for less economically developed countries which do not have a well developed air pollution monitoring network.
I have a few observations regarding the paper:
1. It would be appropriate to highlight the purpose of this study in the introductory part of the article.
2. In the introduction, it would be also relevant to present whether similar research on NO2 air pollution in the troposphere has been carried out by using the data on pollutant concentrations, meteorological parameters obtained from satellite and applying similar data processing and modeling methods.
3. The methodology takes more than a half of the entire paper. It should be presented more concisely. Meanwhile, the results section should be extended accordingly.
4. There is a lack of justification on why a higher NO2 concentration is observed when the wind blows from the north and west (Figure 11).
5. What is so special about March 24 that the difference between the true ground NO2 and estimation ground NO2 data is the most significant?
6. The information presented in the discussion section (except for the last paragraph) is the same as one presented earlier in the paper.
7. There is no summary of the main findings of the study.
Author Response
1. It would be appropriate to highlight the purpose of this study in the introductory part of the article.
Answer: Thank you, we have added a more specific description of the work lines 118-123.
2. In the introduction, it would also be relevant to present whether similar research on NO2 air pollution in the troposphere has been carried out by using the data on pollutant concentrations, and meteorological parameters obtained from the satellite and applying similar data processing and modelling methods.
Answer: Thank you for your comment, we have added a paragraph regarding similar studies (lines 100-118).
3. The methodology takes more than half of the entire paper. It should be presented more concisely. Meanwhile, the results section should be extended accordingly.
Answer: You are right, thanks. We have moved the COVID-19 section from methodology to the results because it describes more about the fundamental analysis than the methodology. Furthermore, the results section has been extended according to your (other) suggestions.
4. There is a lack of justification for why a higher NO2 concentration is observed when the wind blows from the north and west (Figure 11).
Answer: Thank you for the observation. We have explained why we have a higher no2 concentration when the wind blows towards the north and northwest. Lines 462-465.
5. What is so special about March 24 that the difference between the true ground NO2 and estimation ground NO2 data is the most significant?
Answer: Thank you for the observation, a note about March 24th was added in lines 489-492.
6. The information presented in the discussion section (except for the last paragraph) is the same as the one presented earlier in the paper.
Answer: Thank you. We re-structured the conclusion to be less repetitive.
7. There is no summary of the main findings of the study.
Answer: Thank you. We have added an additional paragraph to the discussion and conclusions, explaining other findings of the work in lines 522-527.
Reviewer 2 Report
The study of ground-level NO2 concentration is very important and this study can be applied to the globally available data to analyze the NO2 impact for different regions. However, there are a few shortcomings of this paper that should be improved.
A few sentences are repeated in the abstract and introduction sections. These should be rephrased.
The quality of the presentation of the results is very poor.
All the plots need to be recreated as the quality is very vague.
Author Response
1. The introduction must be improved. A few sentences are repeated in the abstract and introduction sections. These should be rephrased.
Answer: Thank you for the good observation. We have improved the introduction accordingly, adding a paragraph on similar studies in lines 100-123. Furthermore, we have rephased sentences like:
Abstract: Among the most harmful pollutants, NO2 can cause diseases like Chronic Obstructive Pulmonary Disease (COPD). REPHRASED TO: NO2 which is one of the most harmful pollutants, has the potential to cause diseases such as Chronic Obstructive Pulmonary Disease (COPD).
Introduction: Among the existing atmospheric pollutants, Nitrogen Dioxide (NO2) can be associated with respiratory infections and diseases such as Chronic Obstructive Pulmonary Disease (COPD), which is the fourth leading cause of death globally. REPHRASED TO: Respiratory infections and diseases such as Chronic Obstructive Pulmonary Disease (COPD) are the fourth leading cause of death worldwide and can be linked to Nitrogen Dioxide (NO2).
2. The quality of the presentation of the results is very poor.
Answer: Thank you. We have improved the results according to your suggestions. We moved the COVID-19 (430-444) section to the results because it describes more about the fundamental analysis than the methodology. We have also added the explanation about the wind flowing towards the north and the west (462-465), and march 24th (489-492).
3. All the plots need to be recreated as the quality is very vague.
Answer: The plots’ quality has been improved.
Reviewer 3 Report
Useful results with high potential for applications. More detailed discussion of meteorological conditions role on the base of data gathered would be useful.
Author Response
1. More detailed discussion of meteorological conditions' role on the base of the data gathered would be useful.
Answer: Thank you for the observation. A paragraph explaining additional findings of the work can be found in lines 524-529. We have also improved the results by moving the COVID-19 section (440-457) to the results because it describes more about the fundamental analysis than the methodology. We have also explained the wind flowing towards the north and the west (462-465), and the different behaviour of march 24th (489-492).
Round 2
Reviewer 1 Report
The quality of the article has been significantly improved when the supplements and amendments were made to the article manuscript.
It is great that the authors have taken into account a part of observations and amended the article manuscript according to the comments.
In my opinion, the article may be published in the magazine.
Reviewer 2 Report
Accepted
