MITIGATING THE URBAN HEAT ISLAND EFFECT: The Thermal Performance of Shade-Tree Planting in Downtown Los Angeles
Liguang Li
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe article seems quite interesting and relevant. However, in my opinion, it is necessary to take into account not only the temperature, but also the cloudiness. This factor greatly affects the temperature of the heated surfaces. The authors write about the cloudiness coefficients at their disposal, but neither in Figure 2 nor in the text do they write anything about the use of this factor. In addition, it is worth clarifying the temperature of what is indicated in Figure 2 (air or road surface). I would also like to understand what causes such a significant decrease in temperature in the tree crown in cold weather (lines 209-212)?
Author Response
Comment 1: In my opinion, it is necessary to take into account not only the temperature, but also the cloudiness. This factor greatly affects the temperature of the heated surfaces. The authors write about the cloudiness coefficients at their disposal, but neither in Figure 2 nor in the text do they write anything about the use of this factor.
Response 1: Thank you very much for your suggestion. In the initial data input stage, we did indeed consider the impact of cloud cover data. However, after attempting to find cloud parameter data from numerous weather websites without success, and given that cloud cover parameters require real-time specific measurements, we decided to exclude the influence of cloud cover in this experiment, setting the cloud coefficient uniformly to 0. We also found that many other studies have similarly set this data to simulate clear weather conditions. I have clarified this at the beginning of Section 2.1.2, and will include further exploration of the cloud coefficient in the 5.4 future work section.
Comment 2: In addition, it is worth clarifying the temperature of what is indicated in Figure 2 (air or road surface).
Response 2: Thank you for your suggestion. The temperature data refers to air temperature, and I have already clarified this at the beginning of Section 2.1.2.
Comment 3: I would also like to understand what causes such a significant decrease in temperature in the tree crown in cold weather (lines 209-212)?
Response 3: The reason why the cooling effect in the center of the tree canopy is 1.5°C higher in winter than in summer may be due to the more significant radiative cooling effect in cold weather, reduced heat sources, weaker air convection, and changes in the atmospheric temperature gradient. These factors work together to cause a rapid temperature drop under the tree canopy in cold weather. However, this study did not specifically analyze the causes of this phenomenon, and I believe it would be an interesting research question.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsHere are some suggestions:
1. DISCUSSION: This section needs to rearrange the order and the thinking. The 5.1 section (study’s purpose and hypotheses) is repetitive, and it either deleted or discussed in depth. The 5.3 (implications of the findings) and 5.6 (concluding remarks) both paragraphs can be combined. The subtitle and content in the 5.4 (limitations of the study) section do not match, the limitations are just general words, followed by future prospects. These three parts (5.3/5.4/5.6) need to be rewritten.
2. The model is not verified by actual measurements, and its accuracy is not mentioned.
3. The resolution of some Figures really needs to be improved, as shown in Fig 11, Fig.12……. . The text in the picture is not clear.
Specific comments:
1. Line126-127, Line192-193, both are repetitive.
2. Fig.4 and Fig.10, both are similar. Is it possible to keep only one? In similar cases, please let the author decide.
3. Fig.32, this table is more appropriate in the methods section.
4. Line432, the date, September4, 2022, the basis for the selection should be explained in the study.
5. Fig.37, Feb is No Thermal Stress, Jan is Moderate Heat Stress. Is the criteria from Figure32 (9<UTCI<26, no thermal stress)? If so, Jan is also No Thermal Stress.
6. Fig.37, Fig.38, Fig.39, The information of these three graphs is repeated. Fig.38 is enough.
Author Response
Comment 1: DISCUSSION: This section needs to rearrange the order and the thinking. The 5.1 section (study’s purpose and hypotheses) is repetitive, and it either deleted or discussed in depth. The 5.3 (implications of the findings) and 5.6 (concluding remarks) both paragraphs can be combined. The subtitle and content in the 5.4 (limitations of the study) section do not match, the limitations are just general words, followed by future prospects. These three parts (5.3/5.4/5.6) need to be rewritten.
Response 1: I greatly appreciate the feedback you provided. I have revised the corresponding parts of the Discussion section based on your suggestions, with the changes highlighted in red font.
Comment 2: The model is not verified by actual measurements, and its accuracy is not mentioned.
Response 2: Thank you very much for your suggestion. Due to time and resource constraints, I am unable to conduct field measurements. However, I have found two papers that detail how ENVI-met simulation results show minimal differences from actual measurements when the climate parameters are correctly input. I have included these two references in Section 2.2, and I hope this approach is acceptable. Additionally, I have mentioned field measurements as part of the Future Work section (5.4).
Comment 3: The resolution of some Figures really needs to be improved, as shown in Fig 11, Fig.12……. . The text in the picture is not clear.
Response 3: Thank you very much for your feedback on the image quality. I have revised all the images that did not meet the requirements and uploaded new images that conform to the required size and clarity (including both the main text and the Appendix sections). I have marked the titles of all re-uploaded images in red font for easy identification.
Specific Comment 1: Line126-127, Line192-193, both are repetitive.
Response Specific 1: There is indeed repetition in Line 192-193, and I have already deleted that content. However, Line 126-127 is the first time I mention the five factors in the text. Should I delete this section as well, or is it unnecessary to list the detailed names of the five factors?
Specific Comment 2: Fig.4 and Fig.10, both are similar. Is it possible to keep only one? In similar cases, please let the author decide.
Response Specific 2: Thank you very much for your suggestion. The two images do indeed convey similar content, but during the writing process, I found that a single 2D image cannot express the height information of buildings and trees in the simulation, while a single 3D image cannot fully display the positional relationship between the trees and buildings in the simulation. Therefore, if possible, could both types of images be retained?
Specific Comment 3: Fig.32, this table is more appropriate in the methods section.
Response Specific 3: I completely agree with your suggestion. I have moved the figure to the end of section 2.1.3, and the additional text and figure number have been marked in red font.
Specific Comment 4: 4. Line432, the date, September4, 2022, the basis for the selection should be explained in the study.
Response Specific 4: Thank you very much for your feedback. I chose September 4th because it was the hottest day of 2022, which is the key date for the entire experimental study. I have specifically marked the dates of the hottest and coldest days of 2022 in Section 2.1.2 (Input Climate Data) and Section 4 (Results) to prevent any unnecessary confusion for the readers.
Specific Comment 5: Fig.37, Feb is No Thermal Stress, Jan is Moderate Heat Stress. Is the criteria from Figure32 (9<UTCI<26, no thermal stress)? If so, Jan is also No Thermal Stress.
Response Specific 5: Thank you very much for your careful observation. Indeed, as you suspected, there was an error in my expression. I have already corrected the relevant parts in both the chart and the text, and marked them in red font.
Specific Comment 6: Fig.37, Fig.38, Fig.39, The information of these three graphs is repeated. Fig.38 is enough.
Response Specific 6: I believe your suggestion is reasonable, so I have deleted Figure 37. However, I think the thermal stress evaluation and the ranking of cooling effects by month in Figure 39 are necessary to keep, so I have retained those parts in Figure 39.
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsThe article under review examines an important issue related to urban spatial planning, which is ensuring comfortable urban conditions through optimized tree placement. The effect of urban heat islands, as discussed in the article, exacerbates heat conditions and leads to prolonged periods of unhealthy and hazardous environments for both humans and other living organisms.
From this point of view, the study presented by the authors has an important meaning, since rational tree planting not only reduces the ambient temperature but also has a positive effect on air quality, creating conditions for the development of a comfortable urban environment. Usually, park areas are responsible for this in cities, but if this can be done in residential buildings, of course, such an approach deserves consideration.
COMMENTS
1. I recommend that the authors rework the Abstract, highlighting the scientific problem that is considered in the article. The scientific problem is the lack of knowledge and methods for solving the problem that they formulate right at the beginning of the Abstract.
2. The last paragraph of the introduction formulates the purpose of the study. This is correct. I would recommend that the authors strengthen this paragraph by stating that currently there are no clear methods and approaches, as demonstrated by the review of literature.
3. Figures 11, 12, 17, 21, 24 and other similar ones are of very poor quality. Please bring the drawings into compliance with the magazine requirements, 300 DPI and 1000 pixels on the short side.
4. I recommend expanding the Discussion section by comparing the results obtained by the authors with data from other researchers. Authors can provide quantitative comparison data, positive methodological results that may be useful to other researchers, etc.
In general, the article makes a good impression.
Author Response
Comment 1: I recommend that the authors rework the Abstract, highlighting the scientific problem that is considered in the article. The scientific problem is the lack of knowledge and methods for solving the problem that they formulate right at the beginning of the Abstract.
Response 1: Thank you very much for your feedback on the abstract section. I have followed your suggestions and emphasized the scientific problem in the first half of the abstract, highlighting the novelty and originality of the paper. The new abstract has been marked in red text.
Comment 2: The last paragraph of the introduction formulates the purpose of the study. This is correct. I would recommend that the authors strengthen this paragraph by stating that currently there are no clear methods and approaches, as demonstrated by the review of literature.
Response 2: Thank you very much for your feedback on my research objectives. I believe your suggestions are absolutely correct. I have specifically emphasized the issues in the current literature and the incompleteness of existing strategies for optimizing tree placement at the beginning of the last paragraph in the introduction. The newly added text has been marked in red.
Comment 3: Figures 11, 12, 17, 21, 24 and other similar ones are of very poor quality. Please bring the drawings into compliance with the magazine requirements, 300 DPI and 1000 pixels on the short side.
Response 3: Thank you very much for your feedback on the image quality. I have revised all the images that did not meet the requirements and uploaded new images that conform to the required size and clarity (including both the main text and the Appendix sections). I have marked the titles of all re-uploaded images in red font for easy identification.
Comment 4: I recommend expanding the Discussion section by comparing the results obtained by the authors with data from other researchers. Authors can provide quantitative comparison data, positive methodological results that may be useful to other researchers, etc.
Response 4: I believe your suggestions are very reasonable. I have rewritten the part of the discussion comparing my findings with other studies and introduced specific data, making the quantified results more directly helpful to other scholars.
Author Response File: Author Response.docx
