Synchronization, Decoupling, and Regime Shift of Urban Thermal Conditions in Xi’an, an Ancient City in China under Rapid Expansion
, Wenping Yuan 4,5, Yuanyuan Li 1,2 and Yiping Wu 6
Round 1
Reviewer 1 Report
All my concerns have been answered.
Author Response
Thank you for your affirmation! your suggestion is very helpful to our article.
Reviewer 2 Report
Manuscript ID
- Old: remotesensing-1646656
- New: remotesensing-1721777)
Title: Synchronization, decoupling, and regime shift of urban thermal conditions in Xi'an, an ancient city in China under rapid.
The authors combined existing and new approaches to analyze the temporal and spatial patterns of the thermal environment quantified as surface urban heat island (SUHI) and land surface temperature (LST) for Xi'an, China.
- Most of my comments have been answered by the authors, but I still have a few doubts that need to be precise. More importantly, I couldn't find any validation in this work, which is critical for these studies.
Comment 1.
- Can authors please specify their primary focus of research instead of mentioning "this is not the focus of our study" or "that it is not the focus of our study"?
E.g., Authors' Responses (mentioned Below)
- Land-use change is indeed related to temperature, but this is not the focus of our study.
- Although NDVI and FVI are essential factors affecting the thermal environment, they are not the focus of this study.
- Yes, air temperature data from ground stations (sparse in space) can show air temperature trends, but their movements might differ from surface temperature.
Reviewer concern
No doubt, the papers aim to propose a new method for studying heat islands, DTCA, But all the mentioned factors are not crucial for future research; these issues are relevant to even this research, which can't be ignored. For example, in Line 367-369. Authors mentioned
"That is, after these periods, the temperature difference between these sites and the study area increased than before."
There must be some factors that cause the alteration of temperature. But as per the author, the factors mentioned above are not the focus of this research.
Line 142-148. The land cover % represents the dominance of vegetation and cropland. Several previous research also indicated that green fraction cover is so helpful in minimizing the impact of UHI. But again, I couldn't understand why vegetation is not the authors' primary focus for this study.
Comment 2. (Authors Response 11)
MODIS data resolution is still my main concern. No doubt, MODIS data have been widely used for studies, but I am concerned with a ( 1 kilometer (km) spatial resolution in a 1,200 by 1,200 km grid)) for 0.01912, 0.003, 2, and 2.3 square kilometers . The focus study area would be covered by just 1 or 2 cells of MODIS data, and what if any value of that cell is missing? How that data can be considered authentic. So I suggested validating the temporal trends with AIR data, but the authors said that's not even their focus.
I also read the information "mentioned in section 4.5 Limitations and opportunities),
My question was, Nowadays, in the era of cloud computing, GEE, and the presence of several high-resolution satellite imageries, why do the authors need to use MODIS products with a low resolution that even doesn't seem authentic to their small study area? "In points km2), Why don't the author generate their own LST maps? Also, there are several free products for LULC to extract urban areas and Land use??
Also
It required proper evidence from literature where they used MODIS product (with a 1 kilometer (km) spatial resolution in a 1,200 by 1,200 km grid) product for that small area (with an area of 0.01912 154 and 0.003 square kilometers) and then didn't validated their results with ground observations, Or with any other product.
Comment 3.
Line 233. (section 2.6). Please add proper evidence to validate your method. Authors are proposing a new approach by which they will add something new to the literature. In the future, maybe other people will follow the same method (as an existing algorithm) for which authentication is required. Then how about the calculation procedure/Equation or formula etc.? Response 1 to the reviewers is not satisfactory. I needed this information in the manuscript to ease the readers to understand this method better and follow. So make is apparent in the manuscript.
Comment 4.
For Section 3.2. I previously recommended following the work,
Stewart, I.D.; Oke, T.R. Local climate zones for urban temperature studies. Bull. Am. Meteorol. Soc. 2012, 93, 1879–1900
This is important to consider while studying the "Zones Temperature." But I couldn't find any details. Please specify.
Comment 5.
Line 167. The LST period is 2000-2018, but later in line 185, also figure 2. The urban boundary is for 2000-2015 (which may be OUA), so how about the NUA period? Where the authors have mentioned it, Even figure 2 contains the OUA, Not NUA. Please specify.
Comment 6.
Line 402. (Section 4.1), Statistical vs. double temperature curve analysis" needs to be strengthened with solid literature to validate the results of "double temperature curve" instead of presenting the essential information. It seems so weak that all prover evidence from previous literature proves the method's accuracy.
Comment 7.
Figure 7. Mentioned four color lines present the Functional zones. How about the" Gray color" there? Please elaborate on that one as well.
- Figure 4 resolution I already had described my results above. The resolution is so weak.
Some minor corrections.
- Section 2.1. Study area. Previously I said" mention the exact study area in Sq. Km," but yet I could only find the "Zones" area,
- Line 134. Space between "mm[46].
- Line 136-137. "(Error! Reference source 136 not found.)."
- Line 225. Any reference for the "Mann-Kendall method."
- 252-253. Consider rewriting.
- Line 368. "Than before" seems unnecessary
- Line 631. Is there any supplementary material attached to the manuscript?
- Line 639. These statements seem irrelevant here.
- Line 445. (Figure 4Figure 3) ??
- Line 468. "(Figure 6Error! Reference source not found.).
- Line 537. (Figure 8Error! Reference source not found.).
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 3 Report
This study analyzed the temporal and spatial patterns of the thermal environment from 2000 to 2018 in Xi’an, especially for different functional zones and heritage sites. In addition, a DTCA method is proposed to reveal time-sensitive changes in temperature regimes. The paper is well written. To further improve the manuscript, more details are suggested to be added.
- The SUHI is calculated for the summer season only. Why not considering other seasons?
- The maximum temperature value in a season is used for calculation, which may have the risk of occasional errors. Why not using the mean value?
- More technical details are needed for the DTCA method. For example, How to perform the piecewise regression to make sure the correctness of the solid fitting line in Figure 7? How to determine the breakpoint, quantitatively or by visual assessment? Can DTCA quantify the temperature regime shift or just indicate the warming or cooling trend after the breakpoint?
- Figure 8: The background temperature is viewed as the mean of the whole city. Accordingly, the temperature difference of the four historical heritage sites with the background may come from the different functional zones or the landscape. The difference between the historical heritage sites and their surrounding pixels would be more meaningful?
- Validation is lacked. For example, the accuracy of the LST products in the study area is not clear. The correctness of the DTCA result (the breakpoint) is not clear. If possible, a validation is suggested.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors have addressed all my suggestions, and the manuscript is now significantly improved and acceptable for publication after some minor error check
Line 135. (Error! Reference 135 source not found.).
Line 280. (Figure 5Error! Reference source not found.)
Line 446. (Figure 4Figure 3)
Line 469. (Figure 6Error! Reference source found.).
Author Response
Thank you for your comments! Your suggestions have greatly improved the article. We correct the errors you mentioned.
