I congratulate the authors for their high-quality work developing a theoretical approach to estimate the lidar ratio values for CALIPSO aerosol

models. The research results can be used to evaluate the extinction profiles of atmospheric aerosols by using CALIPSO data. The paper is well written with an excellent logical presentation sequence. The methodology is clearly outlined and based on valid assumptions. The authors describe the approach limitations and expected sources of uncertainties. The authors compared their results to ground observations and results from other consolidated and published results, demonstrating the research's accuracy and contribution to atmospheric science.

However, there are some issues that the authors should work on before the paper's publication:

a) There are a few typo errors that I found and highlighted in the attached file;

b) I'm afraid I have to disagree with the statement in line 300 when the authors discuss the increase of the backscattering coefficient with relative humidity. Figure 3 shows that the backscattering coefficient sensitivity to relative humidity is higher for clean continental aerosols than urban and polluted continental aerosols. Maybe the line patterns in the figure are hard to read in black and white, making it hard to read the information from the plot. I suggest preparing the figure using colors or a continuous line for the clean continental and marine continental for better identification;

c) I suggest that the authors modify the statement in line 308. According to Figure 6(e), both wavelengths show an increase in LIDAR ratio, but 532 nm has a more significant increase than 1064 nm. Also, the LIDAR ratio values are lower at 1064nm than at 532nm;

d) I recommend using  (a), (b), and (c) instead of (c), (d), and (e) in Figures 4 and 6.

e) The Figures 1 to 6 look like the graphs are in low resolution. Their presentation quality can be improved.

Once again, congratulations for the good work.

Please refer to the attached file.

(1) The authors claimed that they developed a physics-based theoretical approach to estimate lidar ratio values for CALIPSO aerosol models. In my point of view, this study employed the Mie theory to simulate lidar ratios using different aerosol models but did not develop any new methodology.

(2) The paper is not well written, especially for the poor punctuation.

For example, Line 99, ‘this study, attempts to’ -> ‘this study attempts to’; Line 163, ‘Bohren, and Huffman’ -> ‘Bohren and Huffman’.

(3) “backscattering coefficient” rather than “backscatter coefficient”, for example in Line 164, please change it throughout the whole paper.

(4) Line 121-150, The geometric standard deviation should be dimensionless.

(5) In Line 166 and 169, it was declared that n_r and n_i were used for real part and imaginary part of the refractive index, respectively. However, the symbols m_r and m_i were used instead in Table 1, 2, and 4.

(6) In Line 113 and 200, it pointed out that r_m represented median radius. But ‘mean radius’ was used instead throughout the paper.

(7) The unit of r_m was not specified in Table 1, 2, and 3.

(8) What do ‘Nr’ and ‘Dr’ mean in Figure 1 and 2.

(9) I disagree with the authors that the simulated lidar ratios were consistent to the in-situ values from AERONET. As can be seen from Table 7 to Table 11, the lidar ratios were underestimated compared to the in-situ values in most cases, especially for the cases of Category-1 and Category-3.

(10) Table 13, the simulated lidar ratio of dust at 1064 nm is much smaller than those in CALIPSO operational algorithm; the simulated lidar ratio of Clean Continental at 532 nm and Clean Marine at both wavelengths are much larger than those in CALIPSO operational algorithm, why?

(11) Why did the lidar ratios decrease when the relative humidity was between 0~80% while increase when the relative humidity was between 80~99% ?

(12) Significant progress has been made in the research community for improving the aerosol optics modeling. This manuscript is mostly relied on Hess (1998) that was published 25 year ago. We all know that lidar ratios are sensitive to the partilce nonsphericity, heterogeneity, and the absorption. Relevant discussions related to these issues and the weakness of the present study should be included.

General Comments:

This manuscript applies Mie scattering theory to estimate the lidar ratio for different CALIPSO aerosol models. From a technical perspective, this study lacks significant innovation. Additionally, the analysis of the impact of relative humidity on the lidar ratio, based on the estimation results, holds some scientific value. Therefore, it is recommended to reconsider the acceptance of this study after the following issues have been well solved.

Specific Comments:

1) Many studies have already computed the Lidar ratio based on Mie scattering theory and analyzed the influence of relative humidity on the lidar ratio, such as Zhao et al. (2017). However, there are relatively few studies that apply these computed results to the retrieval of CALIPSO data. The author should, upon calculating the Lidar ratio, conduct an in-depth analysis by combining CALIPSO observational data to investigate the impact of relative humidity or aerosol hygroscopic growth on the retrieval of CALIPSO data.

2) Mie scattering theory is only applicable to spherical particles. In the CALIPSO aerosol models, several are predominantly non-spherical, and it's evident that Mie scattering theory cannot be applied to them. Some of the results in section 4.1 of this manuscript also confirm this. The author should, considering the results from section 4.1, distinguish between CALIPSO aerosol models for which Mie scattering calculations are applicable and focus the subsequent analysis only on those aerosol models where Mie scattering is applicable. It would be inappropriate to simply summarize the comparison results for various CALIPSO aerosol models in section 4.1 as "good agreement."

3) The calculation results regarding the impact of relative humidity on lidar ratio and backscattering coefficient offer many details for further exploration. For instance, lidar ratio appears to exhibit opposite trends with relative humidity variations at low and high relative humidity levels. Furthermore, if the vertical axis of Figures 3-6 could be presented in relative terms, it might allow for a better comparison of gradient differences between different curves.

Reference:

Zhao, G., Zhao, C., Kuang, Y., Tao, J., Tan, W., Bian, Y., Li, J., and Li, C.: Impact of aerosol hygroscopic growth on retrieving aerosol extinction coefficient profiles from elastic-backscatter lidar signals, Atmos. Chem. Phys., 17, 12133-12143, 10.5194/acp-17-12133-2017, 2017.