Effectiveness of Using Calcite as an Aerosol to Remediate the Urban Heat Island

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you very much for inviting me to review the manuscript. I am honoured to have the opportunity to evaluate such an interesting and important study. I am pleased to contribute to the review process of this article, which addresses key issues related to solar radiation management and its impact on urban heat islands.

The current title of the manuscript, "Atmospheric Effects of Calcite Particulate Aerosols," is too general and does not fully reflect the scope and specificity of the research conducted. The title should more precisely reflect the key aspects of the study, such as the effectiveness of calcite in solar radiation management and its potential application in reducing the urban heat island effect. I recommend changing the title to better convey the specifics of the study. It should include the main goals and findings of the research, such as the use of calcite for solar radiation management, its impact on urban temperatures, and its effectiveness in different climatic conditions. This way, the title will better attract the attention of readers interested in specific aspects of geoengineering and climate management, while also providing precise information about the article's content.

The keywords should be well-chosen and avoid repeating words from the title of the article. In the title "Atmospheric Effects of Calcite Particulate Aerosols," the word "calcite" is repeated. It is therefore recommended to replace the keyword "calcite" with another term that better captures the specificity of the research without duplicating words from the title. Please replace the word "calcite" with another term that does not repeat in the title but still accurately describes the research topic.

In evaluating the grammar of the manuscript, several significant issues can be noted. In some places, there are word repetitions, which unnecessarily complicate sentences and may confuse the reader. For example, the sentence: "A single column model models was used to predict the diurnal temperature variation..." contains a repetition of "models." It should be: "A single column model was used to predict the diurnal temperature variation..." The syntax of some sentences is unclear and too complicated, which makes the text difficult to understand. For example, the sentence: "The goal of this paper is to provide numerical tools in investigating the creation of plumes of particulates at lower altitudes over cities in order to cool them." is somewhat unclear and lengthy. A better structure would be: "The goal of this paper is to provide numerical tools to investigate the creation of particulate plumes at lower altitudes over cities for cooling purposes." In several instances, the use of grammatical tenses is inconsistent, which may affect the precision of the message. Additionally, some phrases are too colloquial and could be replaced with more formal language, which is required in scientific publications. For example, the sentence: "Calcite will be used to mitigate high temperatures because it has exceptional radiant properties." could be more formally written as: "Calcite is used to mitigate high temperatures due to its exceptional radiant properties." The use of singular and plural forms in some sentences is inconsistent, which can cause confusion. Overall, the manuscript requires careful proofreading for grammar and style to improve its clarity and formality.

Please pay attention to this example sentence: "A single scattering albedo single scattering albedo of 0.94 was chosen." Such repetition suggests a lack of care in editing the text and negatively impacts its professional reception. The correctly formulated sentence should read: "A single scattering albedo of 0.94 was chosen." This error indicates the need for thorough proofreading before publication to avoid similar mistakes.

The current abstract includes the basic elements, but it could be improved by adding more detailed information about the aim, methodology, results, and conclusions of the study, making it more complete and informative. I therefore propose its elaboration.

The introduction lacks references to some more recent studies and reviews regarding global efforts and discussions on SRM. Examples of such studies include works that discuss the long-term ecological, economic, and social impacts of geoengineering, as well as political and ethical reviews on the global implementation of SRM. I therefore recommend including references such as: Reynolds, J.L. (2019) - "The Governance of Solar Geoengineering: Managing Climate Change in the Anthropocene," or MacMartin, D.G., Kravitz, B., Long, J.C.S., and Rasch, P.J. (2016) - "Geoengineering with stratospheric aerosols: What do we not know after a decade of research?". Including these publications in the introduction would allow for a more complete and comprehensive presentation of the current state of knowledge on SRM, enriching the context and emphasising the significance of the research conducted.

The "Methods" section describes the use of the SCAM6 column model and the modifications made, which are important, but it lacks a more detailed discussion on how these changes were made and their impact on the modelling. Test cases are presented, but there is a lack of detailed analysis and justification for the selection of these cases. The description of input data modifications to simulate low humidity conditions is crucial, but more details about data sources and the methodology used for these modifications would be helpful. Although the section describes assumptions, such as turning off relaxation in the model, there is a lack of a more detailed discussion on the consequences of these assumptions for the results and their interpretation.

The "Results" section of the manuscript is detailed and covers outcomes for different scenarios, but it requires improvement in several key aspects. The description of test cases, such as "OK-base," "OK-L29," "OK-L22-24," as well as "Arid-base," "Arid-L29," and "Arid-L22-24," is thorough, but it lacks sufficient explanation of the methodology used to analyse the results, which hinders full understanding of the data. The results are illustrated with graphs, but additional tables could facilitate comparison and interpretation of the data. The analysis of the impact of wind and clouds on the effectiveness of calcite is important, but it lacks detailed information on the analytical methods used. While the inclusion of uncertainties and limitations is positive, it requires more detailed discussion. Overall, the "Results" section is well-organised, but it could be strengthened by adding more detailed descriptions of the methodology, additional tables, and more comprehensive discussion of uncertainties and limitations.

The "Discussion" section lacks key elements that should be included in a true scientific discussion. Firstly, there are no references to any publications, which is a serious oversight. The discussion section should include references to previous research and literature that can confirm or contrast with the findings presented in this study. Without these references, the discussion loses credibility and does not allow for a full contextualisation of the results within a broader scientific framework.

In this chapter, a thorough discussion should be conducted, which includes comparing the results with previous studies and discussing their implications. For example, it would be beneficial to reference studies on the effectiveness of other materials used in geoengineering, such as sulphur, and compare them with the effectiveness of calcite. Additionally, the discussion should consider the potential long-term ecological and health effects, which would be crucial for assessing the practical utility of calcite in solar radiation management.

The "Conclusions" chapter of the manuscript contains a basic summary of the research findings; however, it lacks deeper analysis and context, which limits its scientific value. The current text focuses on stating that calcite effectively reflects shortwave solar radiation and can significantly lower urban temperatures, which is an important finding. Nevertheless, this chapter should include a more detailed discussion of the implications of the results, comparisons with previous studies, and suggestions for future research. At present, the "Conclusions" chapter is too general and requires significant improvement to meet scientific standards and provide a more comprehensive overview of the conducted research.

Comments on the Quality of English Language

The quality of the English language in the manuscript is subpar and requires extensive revision. There are numerous grammatical errors, awkward phrasing, and instances of word repetition that detract from the professionalism and readability of the text. For example, the sentence "A single column model models was used to predict the diurnal temperature variation..." contains a redundant repetition and should be corrected to "A single column model was used to predict the diurnal temperature variation." Such errors indicate a lack of careful proofreading.

The manuscript also suffers from overly complex and unclear sentence structures, which impede comprehension. For instance, the sentence "The goal of this paper is to provide numerical tools in investigating the creation of plumes of particulates at lower altitudes over cities in order to cool them." is convoluted and should be simplified to "The goal of this paper is to provide numerical tools to investigate the creation of particulate plumes at lower altitudes over cities for cooling purposes."

There are several instances where the use of grammatical tenses is inconsistent, and colloquial phrases are used instead of the formal language required for a scientific publication. For example, the sentence "Calcite will be used to mitigate high temperatures because it has exceptional radiant properties" is too informal and should be revised to "Calcite is used to mitigate high temperatures due to its exceptional radiant properties."

Additionally, there are inconsistencies in the use of singular and plural forms, contributing to further confusion. The manuscript demands a thorough and rigorous review for grammar, style, and clarity to meet the standards expected in academic writing.

Author Response

Thank you to the reviewers from providing extensive helpful comments.  All of the suggested changes have been made.

Comment 1: Change the title.

Response 1: The title has been changed.

Comment 2: Change the keywords.

Response 2: The keywords have been changed.

Comment 3: Improve the grammar.

Response 3: The manuscript has now been extensively edited to improve the grammar.  The revisions are shown in track-changes mode.

Comment 4: Expand the abstract.

Response 4: The abstract has been expanded.  See it in the revised manuscript.

Comment 5: Expand the discussion of SRM in the introduction.

Response 5: The introduction was expanded.  The recommended reference was used.

Comment 6: Include more information about how SCAM6 was modified.

Response 6: New information was added.  See section 2.1.

Comment 7: Improve the results section with further interpretation of the cases, show tables of results, methods and limitation.

Response 7: All of the changes have been made.  For example, see the new Table 1.  This new table was useful for improving the discussion section discussed next.

Comment 8: The discussion needs comparison to other published results.

Response 8: Results were compared to other published papers.

Comment 9: Discuss ecological concerns.

Response 9: Ecological concerns were added to a list of concerns.  I have two drafted full-length papers that consider ecological concerns in great depth.  I believe that it is necessary to focus on weather modification in the current manuscript.  Each paper should have one main topic and not get too distracted.  It would make the paper three times as long if that information was all included here.

Comment 10: Expand the conclusions section with interpretations of results and future work.

Response 10: Done.  See the text.

Reviewer 2 Report

Comments and Suggestions for Authors

Introduction

1. Clarity of Scope: How do you justify focusing on regional weather modification for temperature mitigation while briefly mentioning the global scale challenges of solar radiation management (SRM)? Should the introduction more clearly delineate the difference in scope between global SRM and your regional approach?
2. Operational Plan Explanation: Should the paper provide more details or context about the "operational plan" for creating calcite plumes, given that this is central to the modeling tools being developed?
3. Material Choice Rationale: Why is the reflection of visible light by calcite emphasized, but not the potential for calcite to interact differently with various atmospheric wavelengths? Could additional sources or examples strengthen the rationale for choosing calcite?
4. Health Impact Discussion: Should the preliminary discussion of health impacts be expanded, given that this issue is potentially critical? Would referencing more detailed health impact studies improve this section? Consider including the studies for providing a deeper understanding of the health risks associated with calcite aerosols.
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Interaction of Aerosols with Clouds

5. Atmospheric Interactions: How do the differing effects of calcite’s hygroscopicity before and after atmospheric aging affect the overall modeling outcomes? Should this section elaborate more on these interactions?
6. Impact of Aerosols on Cloud Formation: Is the discussion on how high levels of aerosols may reduce cloud formation sufficiently supported by existing literature? Should this be cross-referenced with studies that explore these dynamics in similar contexts? The reference by Karimi et al. (2021) on the urban heat island effect in cold desert cities could provide additional insights into how aerosols affect atmospheric conditions.
   • Reference: Karimi, A., Mohammad, P., García-Martínez, A., Moreno-Rangel, D., Gachkar, D., & Gachkar, S. (2021). "Surface Urban Heat Island Assessment of a Cold Desert City: A Case Study over the Isfahan Metropolitan Area of Iran." Atmosphere, 12(10), 1368.
7. Regional Focus Justification: Given the focus on arid regions, should the paper discuss more thoroughly how calcite’s interaction with cloud formation might differ in such environments? Would it be beneficial to include studies related to cloud-aerosol interactions in arid versus humid regions?

Materials and Methods

8. Modeling Tools Selection: How does the decision to modify the SCAM6 model account for potential limitations or inaccuracies in simulating calcite's behavior? Would a discussion of alternative models or additional validation strengthen the paper?
9. Code Modification Details: Should the modifications made to account for calcite’s optical properties be described in more detail, particularly in terms of their potential impact on the model’s accuracy?
10. Relaxation Turn-off Justification: Is the decision to turn off relaxation in the SCAM6 model sufficiently justified, considering the implications for modeling accuracy?

Case Selection and Data Handling

11. Case Study Relevance: How does the choice of ARM97 as a case study affect the generalizability of the results, particularly in arid regions? Should there be more explanation or justification for using a humid region’s data as a basis for approximating dry conditions?
12. Data Modification Limitations: Are the limitations of modifying the ARM97 data to simulate arid conditions adequately addressed? Could the paper benefit from a more in-depth discussion on how these modifications might influence the outcomes?
13. Broader Applicability: Should the paper consider discussing how the modified ARM97 case could be adapted or validated against actual arid region data to improve the applicability of the findings?

Suggested References

14. Literature Gaps: Are there any critical references missing that could enhance the discussion of urban heat island effects or other related phenomena? Should references be integrated to provide a more robust foundation for the research? Consider include references that could provide additional insights into the challenges of mitigating urban heat islands, which are relevant to your study of temperature mitigation using calcite aerosols.

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15. Health Impact References: Given the preliminary nature of the health impact discussion, should more specific studies or data on aerosol health effects be included to strengthen this aspect of the paper? The study by Halder et al. (2022) on the urban heat island of Seville city could provide valuable context.

• Reference: Halder, B., Karimi, A., Mohammad, P., Bandyopadhyay, J., Brown, R. D., & Yaseen, Z. M. (2022). "Investigating the relationship between land alteration and the urban heat island of Seville city using multi-temporal Landsat data." Theoretical and Applied Climatology, 2022.
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16. Health Impact of Calcite: To enhance the discussion on potential health risks associated with calcite aerosols, should the paper include the study that explores the impact of mineral-dust particles on lung calcification? Consider include the reference that could be pivotal in discussing the long-term health implications of using calcite in urban environments.

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Comments on the Quality of English Language

While the document is clear and well-structured, focusing on improving sentence structure, word choice, and consistency will enhance the readability and professionalism of the text. Attention to these details will also ensure that the content is accessible to a broader audience.

 

Author Response

Thank you to the reviewers for providing extensive useful reviews.  The changes have been made to the manuscript.

Comment 1:  Clarity of Scope: How do you justify focusing on regional weather modification for temperature mitigation while briefly mentioning the global scale challenges of solar radiation management (SRM)? Should the introduction more clearly delineate the difference in scope between global SRM and your regional approach?

Response 1: The new second paragraph focuses on this issue.  See the revised draft.

Comment 2:  Operational Plan Explanation: Should the paper provide more details or context about the "operational plan" for creating calcite plumes, given that this is central to the modeling tools being developed?

Response 2: There is new descriptions in the introduction and throughout the paper that provide some of this information.  However, there are limits to what can be placed in this paper.  I have written a dozen draft full-length papers discussing different aspects of the operational plan.  It is necessary for this paper to focus on science and leave the engineering and economics to later papers.

Comment 3:  Material Choice Rationale: Why is the reflection of visible light by calcite emphasized, but not the potential for calcite to interact differently with various atmospheric wavelengths? Could additional sources or examples strengthen the rationale for choosing calcite?

Response 3: New text about the choice of calcite was added to the introduction.  The wavelength was discussed in two places (Sections 1 and 2.1).  The necessary properties have been provided.

Comment 4: Health Impact Discussion: Should the preliminary discussion of health impacts be expanded, given that this issue is potentially critical? Would referencing more detailed health impact studies improve this section? Consider including the studies for providing a deeper understanding of the health risks associated with calcite aerosols.

Response 4: New discussion of the health is in the introduction and conclusion.  I have drafted a full-length paper about the health consequences.  Including more of that here would distract the paper from the weather modification science.

Comment 5: Atmospheric Interactions: How do the differing effects of calcite’s hygroscopicity before and after atmospheric aging affect the overall modeling outcomes? Should this section elaborate more on these interactions?

Response 5: See new text in sections 1.1 and 3.

Comment 6:  Impact of Aerosols on Cloud Formation: Is the discussion on how high levels of aerosols may reduce cloud formation sufficiently supported by existing literature? Should this be cross-referenced with studies that explore these dynamics in similar contexts? The reference by Karimi et al. (2021) on the urban heat island effect in cold desert cities could provide additional insights into how aerosols affect atmospheric conditions.

Response 6: Thank you for a link to an interesting paper.  I decided that another new reference talked about this issue more directly.

Comment 7: Regional Focus Justification: Given the focus on arid regions, should the paper discuss more thoroughly how calcite’s interaction with cloud formation might differ in such environments? Would it be beneficial to include studies related to cloud-aerosol interactions in arid versus humid regions?

Response 7: I included a new reference that discusses this effect.  It adds to my existing discussion of cloud interactions in section 1.1.

Comment 8: Modeling Tools Selection: How does the decision to modify the SCAM6 model account for potential limitations or inaccuracies in simulating calcite's behavior? Would a discussion of alternative models or additional validation strengthen the paper?

Response 8: I added discussion in the conclusion about future work including experimental validation.  The methods section discusses how there are limited analytical tools available for this sort of modeling.

Comment 9: Code Modification Details: Should the modifications made to account for calcite’s optical properties be described in more detail, particularly in terms of their potential impact on the model’s accuracy?

Response 9: Additional discussion of the code modification was provided.  Also, note that the code is available in the supplementary materials.

Comment 10: Relaxation Turn-off Justification: Is the decision to turn off relaxation in the SCAM6 model sufficiently justified, considering the implications for modeling accuracy?

Response 10: New text was added to section 2.1 to discuss this.

Comment 11: Case Study Relevance: How does the choice of ARM97 as a case study affect the generalizability of the results, particularly in arid regions? Should there be more explanation or justification for using a humid region’s data as a basis for approximating dry conditions?

Response 11: New text was added to the discussion section to talk about generalizability.

Comment 12: Data Modification Limitations: Are the limitations of modifying the ARM97 data to simulate arid conditions adequately addressed? Could the paper benefit from a more in-depth discussion on how these modifications might influence the outcomes?

Response 12: New text discusses the changes to the data and the limitations.

Comment 13: Broader Applicability: Should the paper consider discussing how the modified ARM97 case could be adapted or validated against actual arid region data to improve the applicability of the findings?

Response 13:  New text related to comment 11 also answered this question.

Comment 14: Literature Gaps: Are there any critical references missing that could enhance the discussion of urban heat island effects or other related phenomena? Should references be integrated to provide a more robust foundation for the research? Consider include references that could provide additional insights into the challenges of mitigating urban heat islands, which are relevant to your study of temperature mitigation using calcite aerosols.

Response 14: New references were added to fill the gaps in apply the results to UHI.

Comment 15:  Health Impact References: Given the preliminary nature of the health impact discussion, should more specific studies or data on aerosol health effects be included to strengthen this aspect of the paper? The study by Halder et al. (2022) on the urban heat island of Seville city could provide valuable context.

Response 15: This useful reference was included.

Comment 16:  Health Impact of Calcite: To enhance the discussion on potential health risks associated with calcite aerosols, should the paper include the study that explores the impact of mineral-dust particles on lung calcification? Consider include the reference that could be pivotal in discussing the long-term health implications of using calcite in urban environments.

Response 16: The response to comment 4 addresses this.

Comment <17>:   While the document is clear and well-structured, focusing on improving sentence structure, word choice, and consistency will enhance the readability and professionalism of the text. Attention to these details will also ensure that the content is accessible to a broader audience.

Response 17:  The paper has now been thoroughly edited for readability.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for submitting the revised version of the manuscript. I am pleased to see that the authors have made substantial improvements in response to the feedback provided. The revisions are well-implemented, particularly in terms of the title, grammar, and overall clarity of the manuscript. The corrections visible in red, along with the strikethroughs, indicate a thorough revision process, which has significantly enhanced the quality of the manuscript.

The title now better reflects the scope and specificity of the study, focusing on the effectiveness of using calcite aerosols for urban heat island mitigation. The grammatical issues that were previously noted, including repetitions and unclear sentence structures, have largely been addressed, resulting in a clearer and more professional manuscript. The overall structure and flow of the text have been improved, making it easier to follow the authors' argumentation and findings.

However, there are still a couple of areas where further refinement could enhance the manuscript:

1. The abstract, while improved, remains somewhat limited in scope. It would benefit from a more detailed summary of the study's objectives, methodology, key findings, and conclusions. A more comprehensive abstract will better capture the attention of readers and provide a clearer overview of the research conducted.

2. The selection of keywords could be expanded to better capture the breadth of the study. In addition to the terms already used, I suggest including keywords such as "Urban Heat Mitigation," "Aerosol Reflectivity," "Geoengineering," "Solar Radiation Control," "Particulate Dispersal," "Atmospheric Modelling," "Arid and Humid Climates," and "Climate Engineering." These additional keywords will help to improve the discoverability of the article for researchers interested in related fields.

Overall, the manuscript is now much improved and is approaching a level suitable for publication. With a few final adjustments to the abstract and keywords, it will meet the high standards expected for scientific publications. I commend the authors for their diligent work in addressing the feedback provided and look forward to seeing this research contribute to the ongoing discussion on solar radiation management and urban heat island mitigation.

Author Response

Comment 1:  The abstract, while improved, remains somewhat limited in scope. It would benefit from a more detailed summary of the study's objectives, methodology, key findings, and conclusions. A more comprehensive abstract will better capture the attention of readers and provide a clearer overview of the research conducted.

Reply 1: The abstract has been rewritten to show objectives, methodology and findings.

Comment 2: The selection of keywords could be expanded to better capture the breadth of the study. In addition to the terms already used,

Reply 2: The suggested keywords have been included.

Reviewer 2 Report

Comments and Suggestions for Authors

The article has had a significant effect and now it can be published in the journal.

Comments on the Quality of English Language

A rich and varied vocabulary can enhance the quality of English. Using precise and contextually appropriate words improves clarity and effectiveness. However, overusing complex words can make the writing seem pretentious or hard to follow.

Author Response

Comment 1: A rich and varied vocabulary can enhance the quality of English. Using precise and contextually appropriate words improves clarity and effectiveness. However, overusing complex words can make the writing seem pretentious or hard to follow.

Reply 1: I was able to find three places where I thought that the use of terminology could be rebalanced.