Numerical Weather Predictions and Re-Analysis as Input for Lidar Inversions: Assessment of the Impact on Optical Products

Round 1

Reviewer 1 Report

Review  Report

Manuscript No. RS-1613263

Title: Numeric Weather Predictions and Re-Analysis as input for lidar inversions: assessment of the impact on optical products             

Authors: Yuanzu Wang et al.

This paper investigates the influence of different atmospheric models (forecast and reanalysis) on the retrieval of the aerosol optical properties (extinction and backscatter coefficients) applying Raman and elastic-only methods on lidar measurements, to assess their use in lidar data processing. The results show that the mean relative deviation of molecular number density is always below ±3%, while larger deviations are shown in the corresponding derived aerosol optical properties, and the size of the deviation depends on the retrieval method together with the different wavelengths. The usage of different models can make a larger deviation on the aerosol extinction coefficient, compared with the results of the aerosol backscatter coefficient. The influence   is mainly related to the deviation in the slope of temperature profile provided by forecast and reanalysis models rather than the absolute deviation of the molecular number density.

The results are of interest to the community, and the paper is well written.  I would recommend it for publication with some minor modifications as indicated on the commented manuscript.

In addition, a more general approach is suggested for further study.  The question can be put in the form of

where F is a parameter retrieved from lidar measurements, λ the wavelength, T and p are the atmospheric temperature and pressure profiles, from which the atmospheric molecular number density can be obtained. The Jacobian

can be calculated either analytically or numerically, perhaps already done in your inversion routines. Present and discuss the Jacobian would be helpful to the topic.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

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Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

In the paper, “Numeric Weather Predictions and Re-Analysis as input for lidar inversions: assessment of the impact on optical products,” the authors explore the impact of various forecast and reanalysis model datasets on backscatter and extinction retrievals from lidar measurements at four EARLINET sites.  While much work has been completed for this paper, and overall, it looks fairly good, I have some comments for improvement.  My major concern is the number of grammatical errors that occur throughout the narrative (explained in more detail below), and in addition, I have several minor concerns/comments.  Thus, due to the combination of this major comment and several minor comments, I recommend a major revision for this manuscript.  The authors should address the comments below in their revisions of the paper.

Major/overall comments:

1. Grammatical errors are found throughout the entire paper, and thus I recommend thorough proofreading/grammar corrections. Some examples of errors include:
   1. Page 1, Line 30: “in” should be “of”.
   2. Page 2, Line 50: “source” should be “sources”.
   3. Page 2, Line 51: Add a comma after “aerosols”.
   4. Page 2, Line 57: “way” should be “ways”.

There are other occurrences, but I will not list all of them here.

Minor comments:

1. Page 1, Line 2: In the title, I suggest changing “Numeric” to “Numerical”.
2. Page 1, Line 30: Define EARLINET.
3. Page 1, Line 46: I recommend stating this as “low aerosol loading scenarios”.
4. Page 2, Line 77: Do you mean “single” here instead of “signal”?
5. Page 3, Line 119: What is meant by “operatively exercise”? I suggest re-wording this phrase.
6. Page 3, Line 144: Since you defined EARLINET in the introduction section, you don’t need to re-define here.
7. Page 4, Table 1: Add “(latitude/longitude)” under the Coordinates label and add degrees symbols to the latitude/longitude coordinates in the table (e.g., before the “N” and “E”).
8. Page 6, Line 253: Do you mean “achieve” here instead of “archive”?
9. Page 6, Line 259: What kind of interpolation is performed? Also, do you think there are large errors introduced when doing this?
10. Page 8, Line 341: Why N+1?
11. Page 8, Line 353: Where did this SNR threshold come from? Did you conduct any sensitivity studies varying this threshold?
12. Page 9, Line 356: Were Monte Carlo techniques used in this study at all?
13. Page 9, Line 361: Are these the values of the instrument detection limits? Where did these values come from?  More explanation is needed here.
14. Page 9, Lines 366-367: Note that tau denotes optical depth, which is the integral of the extinction coefficient, not backscatter coefficient. I would make this clear in the text or modify the equation accordingly.
15. Page 9, Lines 375-377: Regarding the overlap layer assumption, when you state that you “applied” this assumption, does that mean you artificially set a constant value for this layer? More explanation is necessary here.
16. Page 15, Lines 509-513: But what about other differences between these lidar sites (e.g., elevation, meteorological conditions, typical aerosol characteristics, etc.)? Are you assuming all else being equal here?  If so, do you think there can be issues with doing that?
17. Page 15, Line 541: Do you mean “sensitive” here rather than “sensible”?
18. Page 19, Lines 592-593: Why are the deviations at Evora negative but the ones at the other three stations are all positive?
19. Page 21, Line 670: “Backscatter related Aerosol Optical Depth” is not a common phrase in the literature and may be confusing for the reader. I recommend choosing a different name for this.
20. Page 22, Line 680: Shouldn’t there be units for the 0.0015 number? These are “sr”, correct?
21. Page 23, Figure 8b: Add units to the x-axis for the BAOD.
22. Page 25, Line 737: What is the calibration used? Also, is the same calibration range used for each site.  These details should be added to the text.
23. Page 26, Figure 11: In the caption of the figure, please define what the red and dashed lines indicate. Also, please apply this comment to all other figures in the paper.  The captions should clearly explain what each figure is showing.
24. Page 26, Lines 740-741: Why do you think this pattern is occurring?
25. Page 28-29, Lines 795-851 (Conclusions section): In the Conclusions, please re-define all acronyms (e.g., EARLINET, IFS_ECMWF, GDAS, ERA5, etc.).
26. Page 29, Line 850: Do you mean “derive” instead of “drive”?

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

Thank you to the authors for their responses to my concerns and addressing each of my comments in their revised manuscript.  I believe the paper has been significantly improved and thus suggest it be accepted for publication.