An Airborne Visible Light Lidar’s Methodology for Clear Air Turbulence Detection Based on Weak Optical Signal

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript is devoted to development of a method of clear air turbulence detection using a 532 nm visible light airborne lidar system. The simulation was at the conditions when the influence of axial wind speed and atmospheric temperature variations on the molecular backscattering spectrum in the aircraft flight path and vertical wind speed inversion in the clear air turbulence field were taking into account. These results allow to improve the theoretical model and to optimize the structure and parameters of the detection system, and a 355 nm and 532 nm dual-wavelength lidar system can be constructed. The topic of manuscript is important for groups in area of radiolocation, ensuring aircraft safety, remote sensing etc.

There are some points to correct or to make the information more clear:

1)      It is necessary to explain all values and parameters indicated in formulas after or before them. The distance x appeared after formula (2) although it is the variable in (1). The Figure with geometry of measurements including the angles presented in (2) in subscripts would be useful for a clearer formulation of the problem. It is necessary to specify that the parameter “a”=1.339 (108^th line) after (3) because there is the subscript of “a” at aircraft speed in this formula.

2)      Authors write that "the transmittance F_M and F_A" (169^th line) and  "The transmittance R_M and R_A" (177^th line), but before  there are the phrase  "the molecular and aerosol backscattering spectral is R_M and R_A" (168^th line) (it is necessary to clear what the spectral functions  are  R_M and R_A here). The R_M and R_A are apparently  the spectra of transmittance in 177th line.

3)      Authors write "The effect of atmospheric temperature and axial wind speed changes on the transmittance ratio F_M/F_A of IMAF is shown in Figure 3" (208^th-209^th lines) and "F_M(T,υ) /F_A(υ)" is presented in the Figure capture, but the dependence of F_A/F_M(T) is presented in Figure 3.

4)      It is necessary to explain the values of S_π,A(x) S_π,M(x) after formula (10) including subscripts.

5)      Authors propose the improved method of clear air turbulence detection. The data presented the comparison of results obtained by proposed  method and by the methods obtained by other groups (as table or something else) could make the manuscript more informative. 

6)      There are some skipping spaces (e.g. 56^th line “companies(including)”, 113^th line “Organization(ICAO)” etc.) in the manuscript.

This manuscript is written sufficiently clear and describes with details the method of clear air turbulence detection with using a visible light airborne lidar system.

The manuscript can be published after minor revisions.

Comments on the Quality of English Language

This manuscript is written sufficiently clear (but some corrections are necessary) and describes with details the method of clear air turbulence detection with using a visible light airborne lidar system.

The manuscript can be published after minor revisions.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

In our opinion, the manuscript does not demonstrate new results.  The study performed does not contain significant results in the detection of the atmospheric turbulence. Emphasizing this, we do not focus our attention on the accuracy of estimating the characteristics of turbulence, as well as on the spatial scale of turbulent fluctuations.

-        We think that the introduction does not address the problem of turbulence sensing using lidars.

-        «CAT refers to turbulence occurring at altitudes above 6 km and is unrelated to convective clouds». On the one hand, the authors begin their manuscript with the term CAT. This term must be deciphered at the beginning of the introduction of the manuscript. On the other hand, turbulence below 6 km does not occur under clear sky conditions? Authors provide a very strange definition of CAT.

-        One important aspect of this study is that use of lidar for detecting turbulence in a real atmosphere is not given. In this regard, it is impossible to judge the correctness of the proposed approaches and method.

-        We apologize, but the conclusions in this study are poorly written.

 Considering the above, we recommend that authors improve their manuscript to an acceptable article, making it a complete and not a truncated

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Comments to: “An airbone visible light lidar´s methodology for clear air turbulence detection based on weak optical signal”,

 

This work presents a method for CAT detection based to 532 nm airborne lidar using IMAF that detect aerosol backscattering intensity on aircraft flight path. I think this work can be suitable for readers of this journal after minor revisions as follows:

 

1.     In abstract authors could present some data on the preciseness about aerosol conditions of results. This comment allude to line 25: “… for CAT detection, aiming to solve the full coverage problem of CAT detection under various aerosol conditions”.

 

2.     In the introduction, please add more references about the goal of this work.

 

3.     What disadvantages are there when implementing this proposal?

 

4.     How do you turn this method into a practical application

 

5.     Some observations about the edition:

 

a.       Line #84, the vertical velocity variation is not the same letter (font) that implements in equation (1)

b.       Line #110, the turbulence out-scaling, in not the same letter (font) that implements in equation (3)

c.       Figure 4, review the blocks that use the word system.

 

 

Comments on the Quality of English Language

Minor editing of English language required

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Unfortunately, I cannot confirm the correctness of your study in the presented manuscript. In principle, I am not against it, and the topic is very interesting for me and important. But verification of your method is still required. The method itself is interesting, but its performance raises questions. After testing the method, of course, it should be published and the study will be fullfil. Please improve the quality of the manuscript and content. Best regards, for your research.

Author Response

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Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

The aim of the study is complex. Authors have made corrections. This study is complex and conjugated with decision of a lot of subtasks. The manuscript has some pluses and may be considered for publication.