Temporal and Spatial Distribution of Cloud Water Content in Arid Region of Central Asia

Round 1

Reviewer 1 Report

Comments to "Temporal and spatial distribution of cloud water resources in arid region of central Asia" by Zhao et al.

Quantification of the spatial and temporal variability of cloud water resources in the arid regions of central Asia has notable significance for the exploitation of cloud water resources in the arid regions of Central Asia. However, the authors merely explored statistical features of temporal and spatial distributions of cloud water resources for the entire year and different seasons, respectively. Although this topic is intriguing and important, this paper is lack of the dynamic and thermodynamic causes tied to the spatial and temporal variability. Therefore, I can’t be more positive at this stage. I strongly recommend that the authors should present and investigate dynamic and thermodynamic fields responsible for the temporal and spatial distribution of cloud water resources in arid region of central Asia. Such investigation can validate the reasonableness of the statistical features of temporal and spatial distributions of cloud water resources, thus improving the quality of this paper. Overall,  revisions are still required for the current manuscript before the possible publication in Sustainability.

Author Response

Dear Editor and Reviewer:

Thank you for your letter and for the reviewer’s comments concerning our manuscript entitled “Temporal and spatial distribution of cloud water resources in arid region of central Asia” (Manuscript ID: sustainability-1894097).

According to the comments of the reviewer, we have revised our manuscript carefully. The revised portions have been marked in red in the manuscript changes version. The main corrections and the response to the reviewers’ comments are as follows.

Comments to "Temporal and spatial distribution of cloud water resources in arid region of central Asia" by Zhao et al.

Quantification of the spatial and temporal variability of cloud water resources in the arid regions of central Asia has notable significance for the exploitation of cloud water resources in the arid regions of Central Asia. However, the authors merely explored statistical features of temporal and spatial distributions of cloud water resources for the entire year and different seasons, respectively. Although this topic is intriguing and important, this paper is lack of the dynamic and thermodynamic causes tied to the spatial and temporal variability. Therefore, I can’t be more positive at this stage. I strongly recommend that the authors should present and investigate dynamic and thermodynamic fields responsible for the temporal and spatial distribution of cloud water resources in arid region of central Asia. Such investigation can validate the reasonableness of the statistical features of temporal and spatial distributions of cloud water resources, thus improving the quality of this paper. Overall,  revisions are still required for the current manuscript before the possible publication in Sustainability.

Response :Thank you for your suggestion. Our manuscript focuses on the spatial and temporal distribution of atmospheric water vapor resources in the arid zone of central Asia, using the most widely used ERA5 dataset to quantify the distribution of cloud water resources in the arid zone of central Asia from an objective perspective, and to provide a theoretical basis for the rational development of airborne cloud water resources in the region. Adding a description of the field of thermodynamics to the manuscript may deviate from the theme of the article. we will fully consider your suggestions in the subsequent study in order to arrive at a higher quality manuscript.

Author Response File: Author Response.docx

Reviewer 2 Report

Review of “Temporal and spatial distribution of cloud water resources in arid region of central Asia” by K. Zhao et al.

This study characterizes and quantifies the spatial and temporal variability of water vapor and cloud liquid/ice content in the arid areas of central Asia using almost 40 years of reanalysis data. Overall, I think this study contributes to characterizing the long-term variability and trend of water resources of the arid areas of central Asia.

The manuscript is relatively well written; however, I do think the manuscript needs some work on the sentence structure, formatting, and English writing in general, and I have some specific comments (listed below) that I would like the authors to consider before publication.

Main comments:

1.     The authors use cloud ice/liquid content, which are vertically resolved quantities. Whereas, cloud liquid/ice path are vertically integrated quantities (kg/m2), please check this.

2.     Can the authors provide spatial distribution of water vapor, cloud ice/water content variability information, for example standard deviation maps? I think this can be very informative on which area has a higher annual variability in terms of water resources.

3.     Precipitation is another important water source (sink) for land (cloud), can the authors provide characterizations/climatology of precipitation in the study region?

4.     Can the author discuss more on how to reconcile increasing water vapor trend with decreasing cloud ice/liquid content trend, any explanations? Hint: what’s the role of cloud fraction and precipitation? What’s the trend in cloud fraction, as additional water source can be redistributed horizontally to expand cloud cover rather than vertically to increase cloud thickness. Or, perhaps, precipitation was increasing over time in the area, which can also lead to decreasing cloud liquid/ice content.

Editorial comments:

Please check and synchronize all font size and style throughout the manuscript (especially the references!).

Please define acronyms at first use and provide references for them if available, e.g., ERA5, NCEP, CFSR, ISCCP …

Please provide units on all figures.

Please use same colorbar scale for the same quantities on all figures for the ease of comparison, e.g., seasonal, annual comparisons.

Line 172, Figure 3 is being discussed here, please check and correct.

Line 386, please provide the correct ERA5 data doi and reference, as well as for the ISCCP data used.

Author Response

Dear Editor and Reviewer:

Thank you for your letter and for the reviewer’s comments concerning our manuscript entitled “Temporal and spatial distribution of cloud water resources in arid region of central Asia” (Manuscript ID: sustainability-1894097).

According to the comments of the reviewer, we have revised our manuscript carefully. The revised portions have been marked in red in the manuscript changes version. The main corrections and the response to the reviewers’ comments are as follows.

Review of “Temporal and spatial distribution of cloud water resources in arid region of central Asia” by K. Zhao et al.

This study characterizes and quantifies the spatial and temporal variability of water vapor and cloud liquid/ice content in the arid areas of central Asia using almost 40 years of reanalysis data. Overall, I think this study contributes to characterizing the long-term variability and trend of water resources of the arid areas of central Asia.

The manuscript is relatively well written; however, I do think the manuscript needs some work on the sentence structure, formatting, and English writing in general, and I have some specific comments (listed below) that I would like the authors to consider before publication.

Response :Thank you for your suggestion, we have embellished the language of the manuscript.

Main comments:

1. The authors use cloud ice/liquid content, which are vertically resolved quantities. Whereas, cloud liquid/ice path are vertically integrated quantities (kg/m2), please check this.

Response 1:Thank you for your suggestion. The CLWC and CIWC data used in the manuscript refer to the total amount extending from the Earth's surface to the top of the atmosphere.

2. Can the authors provide spatial distribution of water vapor, cloud ice/water content variability information, for example standard deviation maps? I think this can be very informative on which area has a higher annual variability in terms of water resources.

Response 2:Thanks for your suggestion, we have rewritten section 3.3, using linear trend analysis and F-test, and combined the results to get Figure 8, as follows:

A linear trend analysis and F-test were done for water vapour content, cloud ice water and cloud liquid water content, and the results were combined to obtain Figure 8, which shows that: Significantly increasing and slightly increasing areas of water vapour content are found in eastern Kazakhstan and northwestern Xinjiang, China, and significantly decreasing areas are found in western and northern Kazakhstan, western Uzbekistan and western Tajikistan, central and western Kazakhstan, most of Uzbekistan and Turkmenistan, and a slightly decreasing trend in southwestern Xinjiang, China. Significantly increasing areas of cloud ice water content are found in southern Xinjiang and Gansu, south-eastern and south-western Kazakhstan, most of Kyrgyzstan and northern Turkmenistan showing a slight increasing trend, and significantly decreasing areas are found in west-central Kazakhstan, Uzbekistan and east-central Turkmenistan, east-central and south-western Kazakhstan, and west-central Turkmenistan showing a slight decreasing trend. Significantly increasing areas of cloud liquid water content are found in Xinjiang and southern Gansu in China, eastern Xinjiang and Gansu in China, slightly increasing areas in north-central Kazakhstan, significantly decreasing areas in central-western Kazakhstan and west-central Uzbekistan, eastern Turkmenistan, east-central Kazakhstan, western Xinjiang and western Turkmenistan in China with a slightly decreasing trend.

Figure 8. Distribution map of change trend of arid areas in Central Asia from 1980 to 2019(a)water vapor content, (b)cloud ice content, (c)cloud liquid content.

3. Precipitation is another important water source (sink) for land (cloud), can the authors provide characterizations/climatology of precipitation in the study region?

Response 3:Thank you for your suggestion. In fact, we have done an analysis of the relationship between cloud water resources and precipitation, but the distribution characteristics of the two do not show a clear correlation, so we have removed this part from the manuscript.

4. Can the author discuss more on how to reconcile increasing water vapor trend with decreasing cloud ice/liquid content trend, any explanations? Hint: what’s the role of cloud fraction and precipitation? What’s the trend in cloud fraction, as additional water source can be redistributed horizontally to expand cloud cover rather than vertically to increase cloud thickness. Or, perhaps, precipitation was increasing over time in the area, which can also lead to decreasing cloud liquid/ice content.

 Response 4:Thank you for your suggestion. The increase in water vapor content and the decrease in cloud ice water and cloud liquid water content are objective results based on ERA5 data, so we came to a direct conclusion. We researched the literature and found that under the global warming environment, it makes the dryland cyclone weaken, which is not conducive to water vapor transport, making the cloud ice water and cloud liquid water content decrease, and the additional water source level you mentioned expands the cloud distribution and precipitation increases with time, which also leads to the decrease of cloud ice water and cloud liquid water content, these are the factors that affect their content.

Editorial comments:

Please check and synchronize all font size and style throughout the manuscript (especially the references!).

Response :Thank you for your suggestion, we have made changes to the font size and style of the entire manuscript.

Please define acronyms at first use and provide references for them if available, e.g., ERA5, NCEP, CFSR, ISCCP …

Response :Thank you for your suggestion, we have revised it in the manuscript.

Please provide units on all figures.

Response :Thank you for your suggestion, we have labeled the units of each figure in the figure name.

Please use same colorbar scale for the same quantities on all figures for the ease of comparison, e.g., seasonal, annual comparisons.

Response:Thanks to your suggestion, we have recalculated the diagram in python programming as follows: 

Figure 2. Distribution of annual average water vapor content in the arid region of central Asia from 1980 to 2019.(Units: kg·m⁻²)

Figure 3.Distribution of seasonal average water vapor content in arid areas of Central Asia from 1980 to 2019. (Units: kg·m⁻²)(a)Distribution map of average water vapor content in spring in arid area(b)Distribution map of average water vapor content in summer in an arid area;(c)Distribution map of average water vapor content in autumn in arid area; (d)Distribution map of average water vapor content in winter in an arid area.

Figure.4 Annual distribution of cloud ice water and cloud liquid water in the arid region of central Asia from 1980 to 2019. (Units: kg·m−2)(a)Distribution map of cloud water content in an annual average arid area;(b)Distribution map of cloud ice water content in the annual average arid area.

Figure 5. Seasonal average distribution of cloud liquid water and cloud ice water in arid area of Central Asia from 1980 to 2019.(Units: kg·m⁻²) (a) Distribution map of cloud water content in an annual average arid area in spring; (b) Distribution map of cloud water content in an annual average arid area in summer; (c) Distribution map of cloud water content in an annual average arid area in autumn; (d) Distribution map of cloud water content in an annual average arid area in winter; (e) Distribution map of cloud ice water content in an annual average arid area in spring; (f) Distribution map of cloud ice water content in an annual average arid area in summer; (g) Distribution map of cloud ice water content in an annual average arid area in autumn; (h) Distribution map of cloud ice water content in an annual average arid area in winter.

Line 172, Figure 3 is being discussed here, please check and correct.

Response :Thank you for your suggestion, we have made the changes as follows:

It can be seen from Fig. 3 that the highest is in summer, followed by spring and autumn,

Line 386, please provide the correct ERA5 data doi and reference, as well as for the ISCCP data used.

Response :Thank you for your suggestion, we have made changes to the data availability as follows:

The data that support the findings of this study are available on request from the corresponding author.TCWV, CLWV, CIWV, TP, TCC, HCC, MCC, LCC can be obtained at the European Mid-range Weather Forecast Center (https://cds.climate.copernicus.eu/cdsapp#!/yourrequests?tab=form).

Author Response File: Author Response.docx

Reviewer 3 Report

This study uses ERA5 data between 1980 and 2020 to analyze the spatial and temporal distributions of water vapor, cloud water, and ice water over the arid area of central Asia. The analyses of this manuscript are in general basically reasonable, and the basic concepts are introduced in detail. Overall, I believe the research results provide a scientific basis for the rational exploitation of water resources, as the authors stated. I have several concerns regarding the methods, figures, and analyses in this study. The authors also need to proofread the manuscript, as some wordings are hard to read.

Major comments

1. In section 2.2, the authors directly applied the ERA5 data to evaluate and analyze the distributions of those mixing ratios. The reliability of this data for the studied area needs to be explored. I suggest that the authors perform verifications of the ERA5 data using the available surface observations (precipitation, t2m, q2m) within at least one year.

2. Figs. 1-5 are difficult to be followed. Please unify the color bar and add the territory boundaries in these figures. The reader may be unable to identify the locations of the stated countries and regions.

3. Figure 8 shows that the three mixing ratios in 2020 have reduced values compared to those in 1980. Please correct the wording in section 3.3. Moreover, it is not appropriate to use the comparison only between two years (1980 and 2020) to justify the trend analysis.

Minor comments

1. Line 19, Which part of Tajikistan and Kyrgyzstan? Or the full territory of these regions? This is confusing with the areas that have high values.

2. Line 40, rewrite the wording.

3. Line 82, Provide the full names for NCEP and CFSR.

4. Line 107, Spatio-temporal --> spatiotemporal

5. Line 114, a longer time scale and higher spatial resolution  a long-time scale and a high spatial resolution

6. Line 129, 150 mm

7. Line 165 as well as where else, please specify the locations rather than just the country name.

8. Line 172, Fig. 3?

9. Line 179, increased  extended?

10. The caption of Fig. 3 as well as the other figures should be concise. Distribution map of average water vapor content in the arid area in (a) spring, (b) summer, (c) autumn, and (d) winter.

11. Line 322, by us  in this study

12. Line 333, dynamic over-temperature process and micro physical process -> dynamic over-temperature and microphysics processes

Author Response

Dear Editor and Reviewer:

Thank you for your letter and for the reviewer’s comments concerning our manuscript entitled “Temporal and spatial distribution of cloud water resources in arid region of central Asia” (Manuscript ID: sustainability-1894097).

According to the comments of the reviewer, we have revised our manuscript carefully. The revised portions have been marked in red in the manuscript changes version. The main corrections and the response to the reviewers’ comments are as follows.

This study uses ERA5 data between 1980 and 2020 to analyze the spatial and temporal distributions of water vapor, cloud water, and ice water over the arid area of central Asia. The analyses of this manuscript are in general basically reasonable, and the basic concepts are introduced in detail. Overall, I believe the research results provide a scientific basis for the rational exploitation of water resources, as the authors stated. I have several concerns regarding the methods, figures, and analyses in this study. The authors also need to proofread the manuscript, as some wordings are hard to read.

Major comments

1. In section 2.2, the authors directly applied the ERA5 data to evaluate and analyze the distributions of those mixing ratios. The reliability of this data for the studied area needs to be explored. I suggest that the authors perform verifications of the ERA5 data using the available surface observations (precipitation, t2m, q2m) within at least one year.

Response 1:Thank you for your suggestion, we have fully researched the literature and concluded that ERA5 data is the most popular and accurate dataset available, and many scholars have assessed his accuracy, and we can have full confidence in his accuracy, Gong et al. investigated the applicability of the European Center for Medium-Range Numerical Forecasts (ECWMF), Japan Meteorological Agency (JMA), and National Oceanic and Atmospheric Administration Global Forecast System (GFS) numerical model information from July 2010 to July 2013, and the results showed that ECWMF is closer to the actual observations than JMA and GFS (Gong et al., 2015).

2. 1-5 are difficult to be followed. Please unify the color bar and add the territory boundaries in these figures. The reader may be unable to identify the locations of the stated countries and regions.

Response 2:Thanks to your suggestion, we have recalculated the diagram in python programming as follows:

Figure 2. Distribution of annual average water vapor content in the arid region of central Asia from 1980 to 2019.(Units: kg·m⁻²)

Figure 3.Distribution of seasonal average water vapor content in arid areas of Central Asia from 1980 to 2019. (Units: kg·m⁻²)(a)Distribution map of average water vapor content in spring in arid area(b)Distribution map of average water vapor content in summer in an arid area;(c)Distribution map of average water vapor content in autumn in arid area; (d)Distribution map of average water vapor content in winter in an arid area.

Figure.4 Annual distribution of cloud ice water and cloud liquid water in the arid region of central Asia from 1980 to 2019. (Units: kg·m−2)(a)Distribution map of cloud water content in an annual average arid area;(b)Distribution map of cloud ice water content in the annual average arid area.

Figure 5. Seasonal average distribution of cloud liquid water and cloud ice water in arid area of Central Asia from 1980 to 2019.(Units: kg·m⁻²) (a) Distribution map of cloud water content in an annual average arid area in spring; (b) Distribution map of cloud water content in an annual average arid area in summer; (c) Distribution map of cloud water content in an annual average arid area in autumn; (d) Distribution map of cloud water content in an annual average arid area in winter; (e) Distribution map of cloud ice water content in an annual average arid area in spring; (f) Distribution map of cloud ice water content in an annual average arid area in summer; (g) Distribution map of cloud ice water content in an annual average arid area in autumn; (h) Distribution map of cloud ice water content in an annual average arid area in winter.

3. Figure 8 shows that the three mixing ratios in 2020 have reduced values compared to those in 1980. Please correct the wording in section 3.3. Moreover, it is not appropriate to use the comparison only between two years (1980 and 2020) to justify the trend analysis.

 Response 3:Thanks for your suggestion, we have rewritten section 3.3, using linear trend analysis and F-test, and combined the results to get Figure 8, as follows:

A linear trend analysis and F-test were done for water vapour content, cloud ice water and cloud liquid water content, and the results were combined to obtain Figure 8, which shows that: Significantly increasing and slightly increasing areas of water vapour content are found in eastern Kazakhstan and northwestern Xinjiang, China, and significantly decreasing areas are found in western and northern Kazakhstan, western Uzbekistan and western Tajikistan, central and western Kazakhstan, most of Uzbekistan and Turkmenistan, and a slightly decreasing trend in southwestern Xinjiang, China. Significantly increasing areas of cloud ice water content are found in southern Xinjiang and Gansu, south-eastern and south-western Kazakhstan, most of Kyrgyzstan and northern Turkmenistan showing a slight increasing trend, and significantly decreasing areas are found in west-central Kazakhstan, Uzbekistan and east-central Turkmenistan, east-central and south-western Kazakhstan, and west-central Turkmenistan showing a slight decreasing trend. Significantly increasing areas of cloud liquid water content are found in Xinjiang and southern Gansu in China, eastern Xinjiang and Gansu in China, slightly increasing areas in north-central Kazakhstan, significantly decreasing areas in central-western Kazakhstan and west-central Uzbekistan, eastern Turkmenistan, east-central Kazakhstan, western Xinjiang and western Turkmenistan in China with a slightly decreasing trend.

Figure 8. Distribution map of change trend of arid areas in Central Asia from 1980 to 2019(a)water vapor content, (b)cloud ice content, (c)cloud liquid content.

Minor comments

1. Line 19, Which part of Tajikistan and Kyrgyzstan? Or the full territory of these regions? This is confusing with the areas that have high values.

Response 1:Thank you for your suggestion, which we have revised in the manuscript as follows:

The Low value areas are distributed in eastern Tajikistan, central Kyrgyzstan, central Tajikistan and western Xinjiang, China, with the lowest water vapor content of 2 kg·m⁻².

2. Line 40, rewrite the wording.

Response 2:Thank you for your suggestion, we have made changes to the manuscript as follows:

This manuscript uses ERA5 reanalysis data to quantify the spatial and temporal variation of cloud water resources in arid regions of Central Asia, analyzes the factors influencing climate change on cloud water resources, evaluates the development potential of cloud water resources in arid regions of Central Asia, and provides a scientific basis for the rational development of cloud water resources in arid regions of Central Asia.

3. Line 82, Provide the full names for NCEP and CFSR.

Response 3:Thank you for your suggestion, which we have revised in the manuscript as follows:

National Centers for Environmental Prediction (NCEP) and Climate Forecast System Reanalysis (CFSR)

4. Line 107, Spatio-temporal --> spatiotemporal

Response 4:Thank you for your suggestion, which we have revised in the manuscript as follows:

this paper examines the Spatiotemporal distribution and characteristics of cloud water resources in the arid regions of Central Asia.

5. Line 114, a longer time scale and higher spatial resolution à a long-time scale and a high spatial resolution

Response 5:Thank you for your suggestion, which we have revised in the manuscript as follows:

this paper examines the Spatiotemporal distribution and characteristics of cloud water resources in the arid regions of Central Asia.

6. Line 129, 150 mm

Response 6:Thank you for your suggestion, which we have revised in the manuscript as follows:

The average annual precipitation in an arid area is less than 150 mm

7. Line 165 as well as where else, please specify the locations rather than just the country name.

Response 7:Thank you for your suggestion, we have made changes in the manuscript.

8. Line 172, Fig. 3?

Response 8:Thank you for your suggestion, this should be Figure 3, which we have revised in the manuscript as follows:

It can be seen from Fig. 3 that the highest is in summer,

9. Line 179, increased à extended?

Response 9:Thank you for your suggestion, which we have revised in the manuscript as follows:

the water vapor content and the high-value areas extended obviously.

10. The caption of Fig. 3 as well as the other figures should be concise. Distribution map of average water vapor content in the arid area in (a) spring, (b) summer, (c) autumn, and (d) winter.

Response 10:谢谢您的建议，我们对图3,5,9的标题做了修改，具体如下：

Figure 3. Distribution of seasonal average water vapor content in arid areas of Central Asia from 1980 to 2019 in (a) spring, (b) summer, (c) autumn,and (d)winter.(Units: kg·m⁻²)

Figure 5. Seasonal average distribution of cloud liquid water and cloud ice water in arid area of Central Asia from 1980 to 2019.(Units: kg·m⁻²) Distribution map of cloud water content in an annual average arid area in (a) spring, (b) summer, (c) autumn,and (d) winter; Distribution map of cloud ice water content in an annual average arid area in (e) spring, (f) summer, (g)autumn,and (h) winter.

Figure 9. Annual average spatial distribution of total, high, medium and low cloud cover in arid region of central Asia from 1980 to 2019. (Units:”0-1”)Annual average spatial distribution of (a)total cloud cover, (b) high cloud cover, (c) medium cloud cover,and (d) low cloud cover.

11. Line 322, by us à in this study

Response 11:Thank you for your suggestion, which we have revised in the manuscript as follows:

 It is undeniable that the increase of global atmospheric water vapor content is strongly related to global warming caused by us.

12. Line 333, dynamic over-temperature process and micro physical process -> dynamic over-temperature and microphysics processes

Response 12:Thank you for your suggestion, which we have revised in the manuscript as follows:

and global distribution of clouds are the common result of the interaction of dynamic over-temperature and microphysics processes

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I can understand that elucidating dynamic and thermodynamic causes may deviate from the theme of the article. However, for complex terrains such as the central Asia, there could be uncertainties among different reanalysis datasets in describing cloud water resources (e.g., water vapor content). As such, I strongly recommend that the authors should employ other reanalysis datasets, such as the ERA-interim, JRA-55 and NCEP datasets, to compare with your existing results regarding temporal variability and spatial distribution of cloud water resources in arid region of central Asia. Only relatively consistent results among different reanalysis datasets can be convincible.

Author Response

Please find attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Manuscript much improved. Recommend for publication.

Author Response

Response to Reviewer 2 Comments

Dear Editor and Reviewer:

Thank you very much for your recognition of this manuscript. (Manuscript ID: sustainability-1894097).

Reviewer 3 Report

I am satisfied with the revised manuscript and have no further comments.

Author Response

Response to Reviewer 3 Comments

Dear Editor and Reviewer:

Thank you very much for your recognition of this manuscript. (Manuscript ID: sustainability-1894097).