The Retrieval of Drop Size Distribution Parameters Using a Dual-Polarimetric Radar
Round 1
Reviewer 1 Report (Previous Reviewer 1)
The authors revised the manuscript accordingly. Therefore, I would like to recommend it be accepted as in its current form.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report (Previous Reviewer 4)
The paper addresses the issue of non-contact measurement and monitoring of raindrop size distribution (DSD), which is very important for applications such as quantitative precipitation estimation, understanding of microphysical processes, and validation/improvement of two-moment volumetric microphysical schemes. The prediction of rain precipitation models is essential mainly for the changing climatic conditions in the atmosphere. A polarimetric radar disdrometer is used for monitoring. A unified theory based on two-moment scaling normalization is described.
The article contains a very well-crafted overview of the current state with a large number of links to relevant references.
The methodology and models used in this article are described in detail. The article is rich in experimental results and application notes.
Technically, it is very well processed, but again in the article there are mostly problems with the graphical presentation of the results and their processing. Probably the authors didn't read my previous review.
Comments:
There are many images in the article and they are processed in different styles (different font sizes and the way they are displayed and described). The text in some images is huge and in some it is very small. It should be uniform, but it is not that important. It is rather an aesthetic impression that is bad from these pictures. Some images are of very poor resolution.
Again, I did not find plans for future further research in the conclusion.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report (New Reviewer)
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.docx
Reviewer 4 Report (New Reviewer)
The manuscript is a good review of the rain drop size distributions and how dual-polarimetric radars can be utilized to get this relevant data.
I have only three comments.
1. Lines 102-103. "We borrowed heavily from a recent review" sounds like plagiarism, but in a review article understandable. Perhaps a more exact statements of the relation between these two reviews can be formulated?
2. Line 611. "The... operator is not be linear" ?
3. Figure 7. Horizontal reflectivity factor, maybe the unit should be dBZ.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
The manuscript reviewed the drop size distribution and retrieval of DSD using polarimetric radar by explaining the previous studies and new data in South Korea. I think that the authors organized the manuscript very well and explained the history of the DSD model and its application on the polarimetric radar. Therefore, I would like to recommend the manuscript would be published after minor revision.
Comments:
1. Line 19: combing --> combining
2. Line 36: The size distribution --> The drop size distribution
3. Line 73: what is O?
4. Line 192: Authors need to check the font of "probability density function"
5. Line 456: and even R!! --> and even R
6. Line 510: Retrieval Algorithm --> Retrieval algorithm
7. Line 548: 0.3 deg km-1 --> 0.3 deg km-1, respectively
8. Line 568: rexamination --> examination
9. Line 611: Operational Agencies --> operational agencies
10. Line 634: OK --> US
11. Line 670: Panel (a) --> Figure 7 (a)
12. Lines 704-708: Panel --> Figure 8
13. Line 716: panel --> Figure 8
14. Line 748: What is XYOU?
15. I think that the authors described the history of DSDs in many portions of the manuscript, even more than the retrieval of DSDs using polarimetric radar. I think that the authors had better change the title of the manuscript. For example, "The drop size distributions and their retrieval using polarimetric radar".
Reviewer 2 Report
The paper illustrates the long-last history of Drop Size Distribution (DSD) research, describing several models. The article provides an exhaustive review of the main assumptions and it reviews techniques to retrieve DSD parameters from polarimetric radar data. The work sounds scientifically relevant providing a comprehensive essay on DSD research; the language is appropriate and clear.
Although the study is exhaustive, the conclusions could be improved with a couple of statements on further needed investigations and their application to atmospheric and hydrological research.
Minor remarks
Line 16-17 check spell, please
Figure 1. It is not clear if the Figure is original, nevertheless its quality is very poor.
Reviewer 3 Report
This is a paper titled “The retrieval of drop size distribution parameters using dual-polarimetric RADAR ”.
The authors seem to develop a method for rain drop size detection based on a generalized distribution model for polarimetric purposes! Unfortunately, this paper has serious flaws that make this article quite poor. The issue begins with the paper's template, writing style, headings, content, simulation results to the equations, and so on. The current format of the paper appears to be a draft with no specific purpose and it lacks consistency! The literature review is incomplete, and nothing can be verified! I provided them with a couple of major comments, but I do not recommend resubmission. I believe authors should start from scratch and find a perfect article as a template for data presentation.
1- Title: The title is not informative. Please revise it. Furthermore, the title must include both contributions and novelties. Neither contributions nor novelties are highlighted in the topic make it similar to a book chapter. Rain drop size is correct, not drop size.
2- Abstract: Abstract is not acceptable at all. It does not provide a blueprint for the article. The abstract must be concise and cover the topic, problem(s), solution(s), and methodology. It is critical to include some metrics in the abstract. Furthermore, the abstract template does not match the MDPI standards and requires English polishing!
3- Introduction: Unfortunately, the introduction is written in a sloppy style! The background, applications, approaches, problems, and methodologies must all be covered before moving on to the solutions. They must present their approach and solution to the problem, as well as clearly state their pros and cons! It is worth noting that a thorough review of the literature with precise citations plays an important role in a such manuscript submission. It is critical that authors clearly present their contributions and novelties so that potential readers can easily grasp their ideas! The current style suffers from not only average English writing style but also text inconsistencies. The use of incorrect acronyms (such as line 36, 73,...), incorrect writing style (almost the entire manuscript), and erroneous punctuation (such as line 41, 57, 77,...) made understanding of the introduction difficult. In short, the introduction is all over the shop in a haphazard style that does not sound scientific. Please rewrite the entire introduction in a professional manner. Furthermore, what is your contribution to this paper other than the image entities? Could you please explain it in detail?
Thurai, Merhala, Viswanathan Bringi, David Wolff, David A. Marks, Patrick N. Gatlin, and Matthew T. Wingo. 2021. "Retrieving Rain Drop Size Distribution Moments from GPM Dual-Frequency Precipitation Radar" Remote Sensing 13, no. 22: 4690.
4- DSD descriptions and models: The entire section is more like a report than a contribution declaration! What are your novelties? How would you prove it? What is your source formula, and how did you develop (or modify) it? What is your source data and how did you get Figure.1? What do you mean by STAP in Line 124? Did you use SIFT or STAP? How did you classify rain drop sizes and their scales? How did you get rid of the noise effects? What do you mean by the 0th moment as a total number? This entire section suffers from inconsistencies and poor English language! Because of the low resolution, the figures are mostly identical to copy figures and do not correspond to the data!
Most importantly, nothing is verifiable! This paper lacks a verification scenario (both qualitative and quantitative metrics) that allows the equations and modifications to be easily proven. Figures must be justified in light of the outcomes and metrics! This paper cannot be verified in any way!
Additional comments:
1-Please provide a flowchart of your process, along with a quasi-code if possible, for further instructions. The flowchart must be consistent with the details and formulations. This would allow potential readers to concentrate on the contribution and approach presentations.
2- Equation (5) is a generalized distribution model! Please model your considered noise (if it is multiplicative, additive, etc.) and analyze its presence and suppression using your model. A simple formula presentation is not enough. analyze the results of your own research rather than others. In this case, the citation would suffice instead of graph presentation unless absolutely necessary (Such as Fig. 3). How do observational and instrumental uncertainties affect your link budget and data assessment? Please provide a link budget for your noise model. noise is a broad topic and unfortunately, you simplified it to almost a constant!
3- In section.2.1.2, it is necessary to concentrate on the detailed formulation of the scale and geometry of rain drops in the presence of noise! What effect would noise have on the evaluation scenario? It requires actual simulation results and data analysis! Figure 5 is taken from the references and is not based on the analysis. Please be as detailed as possible. Please specify a proper time scale (such as seconds, minutes, hours,...) and try to investigate all of your research on a fixed time-scale! In my opinion, the shorter the time scale, the better the evaluations. Figure presentation must be with high resolution and proper titles and legends.
4- The problem discussed in comment Number.1 still persists in Section. 4! The entire section is inconsistent! Please provide a flowchart for your retrieval algorithm! Meanwhile, could you please specify and verify the Gamma distribution in your research? According to Section. 4, I'm not sure how the Gamma distribution (in general or modified form) or any other distribution model will affect your retrieval algorithm! This is extremely important when it comes to classification. How did you initialize the KNN classification for data analysis?
5- Important topics that must be discussed and categorized in such research include: classification condition (light rain, heavy rain, normal,...), time and season, rain drop scale (large scale, small scale, isometric scale,...), geometry and scale of rain drop, noise distribution, data scale refinement, and, most importantly, the model that must be verified based on provided data. Please keep in mind that classification results (such as Fig. 8) must be based on theory! in the present style what is the meaning of green and red mapping of data! how did you classify and what are your metrics?
6- The most important factor that the author has not addressed is their Dual-polarimetric application! If the topic is related to polarimetric investigation, then the entire research must be oriented toward such claim. In other words, you must modify noise in Dual-polarimetric applications, suppress it in Dual-polarimetric channels, model it in each channel, provide radio line budget and noise suppression based on Dual-polarimetric, and the classification must be oriented toward Dual-polarimetric case! what are the optimum metrics and methods for data analysis then? If you chose the optimum method, how did you justify it in the polarimetric case? furthermore, the stability of analysis must be prove based on different results under different conditions! nothing has been declared regarding the superiority of the method. If everything is discussed from a Dual-polarimetric point of view with proper formulation and discussion, it can be determined whether or not it is suitable for publication! Otherwise, this style is unacceptable.
Noise effects, noise suppression, and rain drop scale (rain drop size), in my opinion, are the key contributions that have been completely overlooked in their formulas and simulation results.
Meanwhile, I noticed similar research from one of the authors, but for a different application (dual frequency instead of dual polarimetry), and I was curious how they differed from previous research!
Reviewer 4 Report
The paper addresses the issue of non-contact measurement and monitoring of raindrop size distribution (DSD), which is very important for applications such as quantitative precipitation estimation, understanding of microphysical processes, and validation/improvement of two-moment volumetric microphysical schemes. The prediction of rain precipitation models is essential mainly for the changing climatic conditions in the atmosphere. A polarimetric radar disdrometer is used for monitoring. A unified theory based on two-moment scaling normalization is described.
In the introduction, similar studies and other works, which follow this research, are described. The need to solve this work is also justified. Relevant references are given.
The next part includes a description of DSDs and their models that are commonly used. Description of DSDs in diameter and moment space is discussed and several DSD models including scaling normalization is presented. Another part consists of the state of the art in retrieval of DSDs.
The most important part of the article is focused on the presentation of the results of DSD retrievals with various methods.
A useful part is the description of the application of the achieved results.
In the discussion there are comments on the achieved results and other problems in this research.
Comments:
Pictures 2 and 6 have worse resolution and quality.
In the article, many quantities are presented in the text in different styles. Scalar quantities should be given as italic style and matrix quantities as bold. Please check the full article.
At the end of the article, it is necessary to mention in detail the plans for further future research in this study.
