Precipitable Water Vapor and Fractional Clear Sky Statistics within the Big Telescope Alt-Azimuthal Region
Round 1
Reviewer 1 Report
Major remarks:
The manuscript needs a major revision as the current format is not suitable for publication in this Journal. The reviewer found inconvinent to evaluate the manuscript since the submitted version did not provide line number.
However, the reviewer found the manuscript interesting, but it needs more clarity and explanation. There are several astroclimatological parameters to justify the quality of an astronomical site. For example, the number of useful nights per year is one of the important parameters and is estimated from the cloud fractional data using a threshold value of cloud data as reported in several references. Further, such statistics of useful night are also varied diurnally (day & night) as well seasonally. In the current work, the authors did not separate day and night from the hourly cloud data.
Further, the authors need to update and improved the scientific content of the manuscript using recent papers reported from potential sites located in the Asian region in particular. Authors can also elaborate the results and can be compared the quality of night in the context of current work. This will increase impact as well scientific content of the paper. For example, there are several recent papers reported on astronomical site survey work from the high-altitude Tibetan plateau, in particular due to the advantages of high-altitude and no monsoon disturbances.
Minor remarks:
1. Pages 1 to 2: Introduction: The authors need to highlight some of the potential astronomical sites located in the high-altitude Tibetan sites in the Asian region (Ningombam et al., 2021; Zhang et al., 2015).
2. Table 1. Need to update the Table 1 with the PWV values from the high-altitude Tibetan Plateau (e.g. IAO-Hanle, Ali Observatories etc.)
3. Page 3, 1st paragraph replace ....'atmospheric optical depth' by 'aerosol optical depth'.
4. Page 3, Section 2: Data:
It is not necessary to mention all the 37 pressure level of ERA-2 data, since it is well known standard products.
5. Page 3, in the Equation 1, the lower limit of the integral should be station pressure equivalent to geopotential height. It is important to note that there is most likely to overestimate the PWV if you do not remove the values which located below the station pressure of your site.
6. Page 4, Equation 2: What are the units of these expression and coefficient ? Readers may find it difficult to digest the Equation 2. Is the Hl indicates water vapor scale height (km) ? Please put the references of this equation so that reader may utilize it. How do you select the proportionality coefficient as 0.439 ? I feel, it may depends on the site as well. Please elaborate the equation also how did you got Ko from Kref.
7. Page 9: Section 4.2: Authors may consider the minimum threshold values of total cloud cover to define useful night for astronomical observation. This is one of the standard procedures to define useful night for astronomical observation as reported in several recent papers (Erasmus and van Rooyen, 2006; Ningombam et al., 2021, Zhang et al.,2015, etc.,).
8. Page no. 17: the Figure number is missing and this Figure also needs to improve.
9. Page no. 16: How do you justify these Equations no. 8-9 in your site and what are the conditions that you have adopted here ? Please elaborate on it ? It is well understood that PWV decreases rapidly as altitude increases.
10. The quality of the Figures need to improve, for example, Figures 3-6 need to improve.
11. Authors have used site name ‘Ali’ in the abstract, however, apparently they have used ‘Ali-1’ in the entire manuscript. Please used only one site name in order to avoid the confusion.
References:
Erasmus D. A., van Rooyen R., 2006, A satellite survey of cloud cover and water vapor in northwest Africa and southern Spain, in Proc. SPIE Conf. Ser. Vol. 6267, Ground-based and Airborne Telescopes. SPIE, Bellingham, p. 62671O,https://doi.org/10.1117/12.669490.
Ningombam S.S. et al., 2021. Evaluation of fractional clear sky over potential astronomical sites. MNRAS, 507(3), 3745–3760, https://doi.org/10.1093/mnras/stab1971.
Zhang J.-C., et al., 2015. Astronomical Observing Conditions at Xinglong Observatory from 2007 to 2014, PASP, 127, 1292.
Author Response
We express our sincere gratitude to the anonymous reviewer for really correct remarks. We have tried to respond to your comments. Thank you. We also ask the reviewer not to pay attention to English. We plan to correct the translation after the manuscript receives the minor status. We pay for translation.
The manuscript needs a major revision as the current format is not suitable for publication in this Journal. The reviewer found inconvinent to evaluate the manuscript since the submitted version did not provide line number.
However, the reviewer found the manuscript interesting, but it needs more clarity and explanation. There are several astroclimatological parameters to justify the quality of an astronomical site. For example, the number of useful nights per year is one of the important parameters and is estimated from the cloud fractional data using a threshold value of cloud data as reported in several references. Further, such statistics of useful night are also varied diurnally (day & night) as well seasonally. In the current work, the authors did not separate day and night from the hourly cloud data.
Further, the authors need to update and improved the scientific content of the manuscript using recent papers reported from potential sites located in the Asian region in particular. Authors can also elaborate the results and can be compared the quality of night in the context of current work. This will increase impact as well scientific content of the paper. For example, there are several recent papers reported on astronomical site survey work from the high-altitude Tibetan plateau, in particular due to the advantages of high-altitude and no monsoon disturbances.
We carefully reviewed the articles and added them to our study.
Minor remarks:
1. Pages 1 to 2: Introduction: The authors need to highlight some of the potential astronomical sites located in the high-altitude Tibetan sites in the Asian region (Ningombam et al., 2021; Zhang et al., 2015).
We add a number of the potential astronomical sites located in the high-altitude Tibet.
2. Table 1. Need to update the Table 1 with the PWV values from the high-altitude Tibetan Plateau (e.g. IAO-Hanle, Ali Observatories etc.)
We add these observatories
3. Page 3, 1st paragraph replace ....'atmospheric optical depth' by 'aerosol optical depth'.
We consider only the optical thickness of the atmosphere due to water vapor.
4. Page 3, Section 2: Data:
It is not necessary to mention all the 37 pressure level of ERA-2 data, since it is well known standard products.
We correct the sentence.
5. Page 3, in the Equation 1, the lower limit of the integral should be station pressure equivalent to geopotential height. It is important to note that there is most likely to overestimate the PWV if you do not remove the values which located below the station pressure of your site.
When we consider the spatial distribution, unfortunately there are no ground pressure data for each grid node in the distribution. Especially in the mountains, it is an important task to obtain the distribution of the correct values of the surface pressure. In this regard, we have used altitude above sea level as the vertical coordinate. We compared our estimates in PWV with radiosounding data. The results are generally not bad, the differences in PWV (in terms of MAE) do not exceed 1 mm.
6. Page 4, Equation 2: What are the units of these expression and coefficient ? Readers may find it difficult to digest the Equation 2. Is the Hl indicates water vapor scale height (km) ? Please put the references of this equation so that reader may utilize it. How do you select the proportionality coefficient as 0.439 ? I feel, it may depends on the site as well. Please elaborate the equation also how did you got Ko from Kref.
We add some information. We used russian reference for this well-known formula. PWV are given in mm. Ko and Kref. Are non-demensional parameters.
7. Page 9: Section 4.2: Authors may consider the minimum threshold values of total cloud cover to define useful night for astronomical observation. This is one of the standard procedures to define useful night for astronomical observation as reported in several recent papers (Erasmus and van Rooyen, 2006; Ningombam et al., 2021, Zhang et al.,2015, etc.,).
We used 20 %, 40 % and 50 % as threshold values to estimate the time of observations at the telescope site (BTA) and in the best location in our opinion (mount Kurapdag with low PWV low cloud cover and small seeing).
8. Page no. 17: the Figure number is missing and this Figure also needs to improve.
We correct it.
9. Page no. 16: How do you justify these Equations no. 8-9 in your site and what are the conditions that you have adopted here ? Please elaborate on it ? It is well understood that PWV decreases rapidly as altitude increases.
We use the water vapor height estimated from radiosonde sounding. We discuss generalized dependence PWV on altitude. We have shown that dependencies described by relations 9 -11 works well for the sites of interest. However we believe that dependencies are more universal for sites in a wide range of elevations above sea level.
10. The quality of the Figures need to improve, for example, Figures 3-6 need to improve.
We try to improve figures (300 dpi).
11. Authors have used site name ‘Ali’ in the abstract, however, apparently they have used ‘Ali-1’ in the entire manuscript. Please used only one site name in order to avoid the confusion.
We correct it
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This study discussed the statistics of precipitable water vapor within the big telescope Alt-azimuthal region. The article is nicely written. And I suggest a minor revision.
Minor comments:
1. The number of keywords should be reduced.
2. Abbreviations should be added after “millimeter/submillimeter”. Then, mm can be applied later.
3. Some equations should be moved in the Section 2 such as Equations (3)-(10).
4. Section of Conclusions should be added after section of Discussion and Results.
Author Response
We thank you for your comments below, we have tried to answer them. With respect and good wishes, Dr. Shikhovtsev Artem
-The number of keywords should be reduced.
We reduce the number of keywords
- Abbreviations should be added after “millimeter/submillimeter”. Then, mm can be applied later.
We add Abbreviation.
- Some equations should be moved in the Section 2 such as Equations (3)-(10).
in order to do not break the structure of the manuscript, we ask the reviewer to leave these equations below
-Section of Conclusions should be added after section of Discussion and Results.
We add results
Author Response File: Author Response.pdf
Reviewer 3 Report
The spatial distributions of PWV, TCC and CBH data are investigated in the study. The paper focuses to astroclimatic conditions within the BTA region. The paper has no originality in terms of this application. The subject is important and the study is valuable in terms of the comparison of estimated and observed PWV data. Some suggestions and comments to the authors are presented below:
1. A basic flowchart of the suggested methodology should be presented in the paper. Thus, the readers can easily follow the application procedures.
2. Check the variables in the equations as “ρ” is water density or specific mass of water. Also, the units of the variables should be given after equations.
3. Conclusions part is missing in the paper. Main conclusions of the study should be explained well.
4. What is the novelty of the paper? The used algorithms are mentioned in the paper. Supported and related studies should be strongly presented in the paper by emphasizing the novelty of the paper.
5. The performance metrics part is very important for the evaluation of application results. For this aim, the performance metrics as NSE, Volume Error (VE), R-squared, etc. from literature should be calculated. Then, they can be given in a table. Because of the importance of the assessment of results, these metrics are widely used in the literature. The new and main papers are suggested below. They should be benefited and cited.
Moriasi, D. N., Arnold, J. G., Van Liew, M. W., Bingner, R. L., Harmel, R. D., Veith, T. L. (2007). Model evaluation guidelines for systematic quantification of accuracy in watershed simulations. Transactions of the ASABE, 50(3), 885-900.
Burgan, H.I., Aksoy, H. (2022). Daily flow duration curve model for ungauged intermittent subbasins of gauged rivers. Journal of Hydrology, 604, 127429. https://doi.org/10.1016/j.jhydrol.2021.127249
6. Literature part is looking weak. Give new and last updated examples from literature about “precipitable water vapor”.
7. The statistical properties as skewness, coefficient of variation, confidence intervals and distribution characteristics, mean, min, max and median, etc. of used data should be given in a table.
8. Discussions part is only a title. Discuss the results.
Author Response
The spatial distributions of PWV, TCC and CBH data are investigated in the study. The paper focuses to astroclimatic conditions within the BTA region. The paper has no originality in terms of this application. The subject is important and the study is valuable in terms of the comparison of estimated and observed PWV data. Some suggestions and comments to the authors are presented below.
It seems to us that the presented manuscript is quite important and has a novelty, since we present the results of research in the vicinity of a new place that we recommend for installing a new millimeter telescope (Mount Kurapdag). In order to estimate the correct values in conditions of heavily rough terrain in the mountains, we propose a new method based on taking into account the heights of different landforms, for example, for a small area around the BTA or Mount Kurapdag. We parameterize the values of PWV to account for local orography within 0.5 degrees around each grid node (site). In addition, we discuss the generalized decrease in values as a function of height above sea level. As a result, we have obtained an improved spatial distributions of PWV.
- A basic flowchart of the suggested methodology should be presented in the paper. Thus, the readers can easily follow the application procedures. We add a flowchart.
- Check the variables in the equations as “ρ” is water density or specific mass of water. Also, the units of the variables should be given after equations. We add information.
- Conclusions part is missing in the paper. Main conclusions of the study should be explained well. We add conclusions.
- What is the novelty of the paper? The used algorithms are mentioned in the paper. Supported and related studies should be strongly presented in the paper by emphasizing the novelty of the paper. We add references and try discuss the novelty which is determined by the proposed method and new statistical data on the content of water vapor in the atmosphere. This is important from the point of view of building a telescope in a new place that we have identified (Mountain Kurapdag )
- The performance metrics part is very important for the evaluation of application results. For this aim, the performance metrics as NSE, Volume Error (VE), R-squared, etc. from literature should be calculated. Then, they can be given in a table. Because of the importance of the assessment of results, these metrics are widely used in the literature. The new and main papers are suggested below. They should be benefited and cited.
Moriasi, D. N., Arnold, J. G., Van Liew, M. W., Bingner, R. L., Harmel, R. D., Veith, T. L. (2007). Model evaluation guidelines for systematic quantification of accuracy in watershed simulations. Transactions of the ASABE, 50(3), 885-900.
Burgan, H.I., Aksoy, H. (2022). Daily flow duration curve model for ungauged intermittent subbasins of gauged rivers. Journal of Hydrology, 604, 127429. https://doi.org/10.1016/j.jhydrol.2021.127249
Literature part is looking weak. Give new and last updated examples from literature about “precipitable water vapor”. The statistical properties as skewness, coefficient of variation, confidence intervals and distribution characteristics, mean, min, max and median, etc. of used data should be given in a table.
We add references and gave a deeper analysis of atmospheric characteristics including cloudiness
- Discussions part is only a title. Discuss the results. We add results.
We express our sincere gratitude to the anonymous reviewer for really correct remarks. We have tried to respond to your comments. Thank you. We also ask the reviewer not to pay attention to English. We plan to correct the translation after the manuscript receives the minor status. We pay for translation.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The scientific content of the manuscript has improved significantly and I am fully satisfied the efforts made my the authors within a sort time. The manuscript can be accepted for publication.
Reviewer 3 Report
I suggest accepting the manuscript.
