Atmospheric Boundary Layer Height: Inter-Comparison of Different Estimation Approaches Using the Raman Lidar as Benchmark

Round 1

Reviewer 1 Report

The study “Atmospheric Boundary Layer height: inter-comparison of different estimation approaches using Raman lidar BASIL as benchmark” by Summa et al is a comparative study of different methods that the atmospheric boundary layer (ABL) height can be found.  These methods range from standard, modern, and new.  The paper does a nice overview of the ABL and its importance as well as the existing methods to find its height.  The paper then sets up a new method of finding the ABL height using Raman lidar signals is described, demonstrated, and compared to existing methods.  The study shows that all methods work well when compared to the standard radiosonde analysis, with an average of all methods working best.  The conclusions of the paper are well supported by the analysis.  

 

Overall the paper is well presented and a nice addition to the existing literature.  My only major comments are that some work needs to be done on the language as some sentences don’t make sense and a bit of reworking where things fall in the paper to make it easier for a reader to understand. I have made a list below for the issues I see, but a good once-over would be advised.

 

  The references need to be checked.  It appears that reference #11 isn’t actually cited in the paper and the order of citations seems to be off.  For example after reference #1 the next one is #3.  If this is a citation style that I am unfamiliar with please disregard this comment.  Also, figure and table are capitalized when referring to a specific figure or table (e.g., Figure 1a or Table 1) anywhere in a sentence. 

• BASIL looks like an acronym but isn’t defined.  For readers unfamiliar with the system just including “The University of Basilicata’s ground-based Raman lidar system (BASIL)” would be quite helpful

• Line 32 as -> such as 

• Line 35 should this be #2 also check the “among others” with editors

• Line 43 reference 11?

• Line 59 MIPA isn’t defined in the body of the paper before the acronym is used, just in the abstract.  Please fix.

• Line 73 WCT isn’t defined in the body of the paper before the acronym is used, just in the abstract.  Please fix.

• Line 84 HyMeX-SOP1 is defined after use.

• Line 93: “ with warm water acting as heat and humidity feeding convective systems” doesn’t make sense.  Perhaps you are missing the work “source”  or something similar.

• Line 99: “in this complex weather conditions” is mixing tenses. Either “in these complex weather conditions” or “in this complex weather condition”.  I assume the former.

• Line 113: comma not need

• Line 116: “these latter dedicated to the collection of used to collect the 532 nm…”.  I assume something needs to be deleted here as this doesn’t make sense.

• Line 123: Previously in the paper “HyMeX-SOP1” was used while here it’s “HyMeX.SOP1” please be consistent.

• Line 134: The sentence here that starts “In order to remove…” is confusing.  Please rework

• Line 179: added “O” in PN2(z)

• Tabs missing started around Line 180 this could just be how the formatting came out on the journal’s end, but you should double check it’s not on your end.

• Line 203: signal-to-noise

• Line 208: state-of-the-art

• Line 231 & 242: “dynamic of the ABL” should be “dynamics of the ABL”. 

• Line 259: Define WPR

• Line 266: “identifies of inversions” should that be “identifies inversions” ?

• Line 274: “and and”.  Too many “and”s.

• Line 329: weel -> well

• Table 2: Why are periods and commas both being used for decimals?

• Table 2: Why are some values given + and others not?

• Table 2: Should have something in the body of the paper or in the table caption what each label represents.  That is, which method is MIPA, Rot (T), WindP, WV, and Mean.  Some might be self explanatory, but not all.  Also, you have Mean in the table and figures, but don’t discuss it at all before the paragraph at line 361.  A simple explanation of what it is while discussing the figures/table would make things less confusing for the reader.  Even something as simple as “Mean is the average of all methods to be discussed later in the paper” would be helpful.

• Figure 2: 16-22 Oct 2010 is in the title.  Please fix.

• Line 372:  “Ramam lidar system BASIL lidar system” Please fix.

• Line 378: “does not allow obtain high”  Please rework.

• Line 390: Please update your values for the signal ratio mutual bias.  Right now you are saying that it has mutual biases of less than 7.72% but in Table 2 there is a value of -8.09%.  Though this is technically correct, it’s the absolute values in these errors that matter.  If this isn’t the case, please add a sentence or two explaining why you care more about positive values than negative values.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript by Donato Summa et al. presents an intercomparison of different approaches estimating the atmospheric boundary layer (ABL) height. Among the approaches, the authors propose to use a methodology based on the application of the derivative or gradient approach to rotational Raman lidar signals from molecular nitrogen and oxygen and roto-vibrational Raman lidar signals from water vapour molecules. Accurate definition of the ABL height is very important for various meteorological applications, including weather forecasting, especially in the Arctic and Antarctic in a changing climate. The approach proposed by the authors for estimating the ABL height using a purely rotational Raman lidar can be applied, for example, in Antarctica, where such a lidar was deployed in 2020 (Liu et al., 2021). Therefore, the relevance of the work is beyond doubt.

The manuscript material and results fall within the scope of Remote Sensing journal and will be of interest to the remote sensing community. My recommendation is to publish the paper in the Journal after some revisions. My several comments (not all) can be found below. All my comments, suggestions, and recommendations are presented in the highlighted version of the manuscript.

Liu F., Wang R, Yi F., Huang W., Ban C., Pan W., Wang Z, Hu H. Pure rotational Raman lidar for full-day troposphere temperature measurement at Zhongshan Station (69.37°S, 76.37°E), Antarctica. Optics Express. 2021. V. 29, N 7. P. 10059–10076.

 

General comment

I did not find any mention of the accuracy of the ABL height estimates obtained using each method separately. For example, since the number of photocounts registered by a pure rotational Raman lidar obeys Poisson statistics, there must be a statistical uncertainty in determining the height from the ratio of lidar signals. I realize that such uncertainties may be insignificant, but then it is necessary to give their estimates and justify their insignificance compared to the estimated ABL height values.

 

Specific comments and recommendations

English. English quality and writing style need to be improved. I recommend professional proofreading of the manuscript.

Decimal point. The authors should use either a decimal comma or a decimal point for all numbers in table 2 and the text of the manuscript.

Abbreviations. Abbreviations in the text, table 2, and figures 2 and 3 are not entered properly. Particular attention should be paid to the fact that some of the abbreviations were not introduced when they were first used in the text.

Equations.

-          It should be "532" instead of "RCS" in the subscript in equation (2). Please clarify which logarithm is meant in equation (2) – decimal or natural (as in the case of a pure rotational Raman lidar (equations (3) and (4))? (lines 145, 148);

-          R and Cp should be explained after equation (6). (line 271)

References in the text of the manuscript.

-          Reference [3] was mentioned before reference [2] (line 35);

-          It should be [38, 39, 40] instead of [38, 38, 40] (line 122);

-          Reference [42] is mentioned after reference [40] (lines 167). Reference [41] is absent in the text of the manuscript;

-          Reference [53] is mentioned after reference [49] (line 243) and before references [49, 50] (line 267). References [51] and [52] are absent in the text of the manuscript;

-          References [57], [58], and [59] are absent in the text of the manuscript (line 308).

List of references. References [2–4, 7–13, 16, 17, 19–21, 23, 25–28, 33, 40–44, 47–49, 52, 53, 55, 57] are given or written incorrectly.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

The paper entitled "Atmospheric Boundary Layer height: inter-comparison of different estimation approaches using the Raman lidar BASIL as benchmark" by Summa et al. presents a new approach to estimate ABLH by using Raman channel signals from lidar which represent the profiles of temperature and water vapor.  The results of the new approach is compared with other methods. The manuscript is interesting. However, some problems should be revised before publication of the manuscript.

 

Line 48-49, a brief description of the methods or ideas in ref. 22 and 23 is necessary.

Line 148, Eq.(2) is inaccurate. ABLH is the height with minimum of logRCS derivative. The same for Eq. (4) in line 177.

 

The description of the new method in Section 2.2 should be improved to be more clear.

A table is needed to briefly summarize the various methods and give the corresponding abbreviations so that the reader can better read the contents of Table 2, Figure 2, and Figure 3.

 

Please give the specific time of the radiosonde data. And it is better to give a scatter plot of the data of various methods regarding the reference method.

 

Figure 3, the discontinuous radiosonde data was used as reference, but how to give the continuous bias in Figure 3?

 

The method was only validated in just 6 days‘ data and did not show a clear advantage over other methods. Is it possible to give more data? Or a detailed case to demonstrate the advantage  of the new method also works.

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

The manuscript presents an intercomparison of several techniques for determining the height of the planetary boundary layer. I must admit the paper is hard to follow, as it appears to have been hastily thrown together as it only provides brief characterizations of results without discussion of why those results might have occurred. 

 

Tell the reader upfront what the reference method is, it’s only defined halfway through the paper. 

 

Try to use tables to summarize the methods and their attributes instead of describing them using language strongly in need of editorial review. This will make the paper easier to read. 

 

Results need to be more completely presented so the reader can better understand the performance of the systems used in the study. Scatterplots showing the regressions between each system and the reference as well as their mean with the reference method are needed. Provide slope and intercept in addition to R². Typically, other atmospheric scientists use a wider variety of metrics in the meteorological literature, such as normalized mean bias, root mean square error, etc., to provide a more complete picture. Go look them up.

 

Kindly provide some physical interpretation explaining differences between methods and/or extreme values.  

 

The authors should also discuss the costs and benefits associated with using multiple methods to determine boundary layer height, as opposed to only using radiosonde data. Also, are there any issues with using radiosonde data to obtain boundary layer height?

 

I also suggest editorial review to address a number of grammatical and syntax errors, a small number of which are shown below. 

 

l. 14 – define acronyms, e.g., BASIL at first use 

l. 87 – conceived

l. 90 – surrounding

l. 193 – you might also mention dew formation

l. 266 – of

l. 276 – the reference method should be identified much earlier with discussion of the merits, advantages and disadvantages of the method.

Table 2 – Unstable

l. 344 – R² is more properly the coefficient of determination, or the square of the correlation coefficient. That is, in this context, how much of the variance in the reference data set is captured by the method.

 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

The authors have addressed all my questions, and I recommend publication of the manuscript.

Author Response

We redid last read check and fixed final errors.. Thanks for the support

Reviewer 4 Report

Paper is fine. I noticed only a few typos and minor grammatical errors. So, please make one more check of spelling and grammar for minor errors. 

Author Response

We redid last check and fixed final errors.. Thanks for the support!