Climate Change of Near-Surface Temperature in South Africa Based on Weather Station Data, ERA5 Reanalysis, and CMIP6 Models

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Impressive study, but suggest to include current assessment methods such as AI and measurement techniques for calibration

Comments for author File: Comments.pdf

Author Response

Answer to Reviewer 1

Comments:

Comment 1: Lines 65-69: Avoid using the long sentence where can be separated into 2 sentences.

Response 1: This long sentence was separated into 2 sentences.

 

Comment 2: Line 114: Please include an inset map of the African continent and indicate the location of South Africa.

Response 2: Figure 1 has been modified to include the continent of Africa.

 

Comment 3: Line 223: 19 weather stations were mentioned as analyzed, but Figure 2 lists 20 weather station locations.

Response 3: The number of analyzed weather stations has been corrected to the value 19.

 

Comment 4: Line 238: The colors indicating specific weather station lines are confusing; it would be better to add labels for the highest, middle, and lowest lines.

Response 4: Station labels for the highest, middle and lower lines were added.

 

Comment 5: Line 243: Explain on how to select that 11 weather stations.

Response 5: Explanation added to text. Next, 10 weather stations were analyzed, covering the observation periods of 1994–2023. Since the Aliwal North weather station was not in operation until 2021.

 

Comment 6: Lines 245-247: Total of 10 weather stations instead of 11 weather stations. Please reconfirm.

Response 6: Information about the 10th station has been added. The article includes an assessment of the significance of long-term trends using the Mann-Kendall criterion at 10 weather stations for 1994–2023.

 

Suggestion:

Comment 7: Include the short definition on NSAT and diagram as well.

Response 7: Short definition of NSAT added.

 

Comment 8: Include the flow chart of research methodology.

Response 8: The methodology is described in detail in the text. It is based on comparing different types of data from different sources. We have added a description of the methodology for calculating correlations and assessing trends and the significance of the results obtained in Section 2 (Materials and Methods) (st.226-238).

 

Comment 9: 3. Conduct on-ground calibration and analysis at random points using advanced temperature measuring devices, which will then be used in accuracy assessment analysis as an add-on, not limited to trend comparison alone.

Response 9: While this is a fascinating aspect of the research, we consider it to be a separate, complete study that we intend to pursue in future work.

 

Comment 9: 4. Utilize the AI techniques, including deep learning, to analyze the extensive dataset spanning from 1940 to 2023, thereby improving the reliability of the data set.

Response 9: While this is a fascinating aspect of the research, we consider it to be a separate, complete study that we intend to pursue in future work.

 

Comment 10: 5. Include an assessment of data accuracy using advanced statistical analysis, rather than relying solely on the comparison shown in Table 4 (Line 462).

Response 10: While this is a fascinating aspect of the research, we consider it to be a separate, complete study that we intend to pursue in future work.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The present manuscript “Climate Change of Near-Surface Temperature in South Africa Based on Weather Station Data, ERA5 Reanalysis, and CMIP6 Models” describes a comprehensive analysis of changing climate in South Africa, mainly through near-surface air temperature (NSAT) by a triangulated methodology viz. data from weather station, ERA5 reanalysis products, and CMIP6 model simulations. The paper makes important support to climate science of the region and gives an insight into changing temperature developments with future projections. Authors tried to integrate the multiple data sources and use of models for assessment of climate scenarios. The manuscript is well-organized and clearly written. Figures and tables are relevant and enhance understanding.

-Data were used from weather station data, ERA5, MERRA-2, NCEP/NCAR reanalyses, CMIP6 model outputs. A range of SSPs (1-2.6, 2-4.5, 3-7.0, and 5-8.5) used in the study, offers a broad view of potential futures. However, it needs be clear the potential limitations of from each model with model performance evaluation or bias correction techniques.

-Results and discussions are written well using both qualitative (maps) and quantitative (statistical summaries) methods. However, maps should be a uniform color scale for more visual comparison.

-There are few grammatical/typographical errors with inconsistent format of tables (e.g., Table 3).

-Define the acronyms (e.g., NSAT, ENSO, PDO) upon first use.

-Conclusion is supported by the given data.

Comments on the Quality of English Language

English is easily understandable, however, few correction for grammer and spelling needed.

Author Response

Answer to Reviewer 2

Comments:

Comment 1: Data were used from weather station data, ERA5, MERRA-2, NCEP/NCAR reanalyses, CMIP6 model outputs. A range of SSPs (1-2.6, 2-4.5, 3-7.0, and 5-8.5) used in the study, offers a broad view of potential futures. However, it needs be clear the potential limitations of from each model with model performance evaluation or bias correction techniques.

Response 1: We fully agree that each individual model has limitations due to its own bias in estimating nominal values. Therefore, we switched to NSAT anomalies and applying the ensemble method.

 

Comment 2: Results and discussions are written well using both qualitative (maps) and quantitative (statistical summaries) methods. However, maps should be a uniform color scale for more visual comparison.

Response 2: Initially, we made maps with the same color scale. But, unfortunately, many features that are now visible on them and discussed in the text of the manuscript became poorly or completely indistinguishable. Therefore, the scales will have to remain different.

 

Comment 3: There are few grammatical/typographical errors with inconsistent format of tables (e.g., Table 3).

Response 3: Corrected.

 

Comment 4: Define the acronyms (e.g., NSAT, ENSO, PDO) upon first use.

Response 4: Corrected.

 

We also appreciate the reviewer’s comments regarding the grammar and spelling of the English language in the article. We have carefully addressed these points and made the necessary revisions.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Your study provides a thorough and well-documented analysis of near-surface air temperature changes across South Africa using a combination of weather station data, ERA5 reanalysis, and CMIP6 model outputs. The integration of multiple data sources over a long time period enhances the robustness of your findings.

However, I offer the following suggestions for improvement:

1. Methods Section:

1. • Please include more explicit detail on the data quality control and homogenization procedures applied to weather station records, as this is critical for trend analysis.

   • Specify whether bias correction or validation was applied to the CMIP6 model outputs relative to observed data.

2. Results:

   • The figures and tables are detailed and informative. However, consider simplifying some figures or moving more complex tables (e.g., model-by-model breakdowns) to the supplementary material.

   • The spatial heterogeneity of temperature trends is well described, but visual clarity could be enhanced in maps with improved legends and clearer contrasts.

3. Discussion:

   • This section is rich and contextualizes the findings well. However, consider tightening the structure to avoid redundancy and better emphasize the key insights.

   • Consider adding a brief subsection discussing the limitations of the study (e.g., model resolution, limitations of reanalysis data in mountainous terrain).

4. Policy and Governance Implications:

   • The application of your findings to urban governance and natural resource management is commendable. This could be strengthened by referencing specific national or regional policy frameworks or suggesting areas where model projections could inform planning (e.g., water infrastructure, urban heat management).

Comments on the Quality of English Language

• While the technical content is strong, the manuscript would benefit from professional language editing. Some sections are overly verbose, occasionally repetitive, or lack clarity due to complex sentence structures.

Author Response

Answer to Reviewer 3

Suggestions for improvement:

1. Methods Section:
   • Comment 1: Please include more explicit detail on the data quality control and homogenization procedures applied to weather station records, as this is critical for trend analysis.

Response 1: Subsections describing correlations and trends have been added to the research methodology and results

• Comment 2: Specify whether bias correction or validation was applied to the CMIP6 model outputs relative to observed data.

Response 2: The text has been supplemented with information describing the methods (st.226-233) for comparing the results of modeling and weather stations, ERA5 reanalysis, and the analysis itself.

2. Results:
   • Comment 3: The figures and tables are detailed and informative. However, consider simplifying some figures or moving more complex tables (e.g., model-by-model breakdowns) to the supplementary material.

Response 3: Thank you for your comment, but we do not see the possibility of transferring some of the tables and figures to additional materials, since we rely on these results in the discussion and conclusions of our work.

• Comment 4: The spatial heterogeneity of temperature trends is well described, but visual clarity could be enhanced in maps with improved legends and clearer contrasts.

Response 4: We have improved some of the figures. But it is not possible to increase the contrast of the fields, since they must have a single scale.

3. Discussion:
   • Comment 5: This section is rich and contextualizes the findings well. However, consider tightening the structure to avoid redundancy and better emphasize the key insights.

Response 5: We find the Discussion section to be well-organized, with clearly defined sub-sections that present information in a logical and concise manner. We respectfully request that the Discussion section be preserved in its entirety, without any reductions.

• Comment 6: Consider adding a brief subsection discussing the limitations of the study (e.g., model resolution, limitations of reanalysis data in mountainous terrain).

Response 6: These limitations are discussed in the text; it is difficult to combine them and put them in a separate section.

4. Policy and Governance Implications:
   • Comment 7: The application of your findings to urban governance and natural resource management is commendable. This could be strengthened by referencing specific national or regional policy frameworks or suggesting areas where model projections could inform planning (e.g., water infrastructure, urban heat management).

Response 7: Thank you for your comment. We have revised the subsection and included the necessary references to local regulatory documents.

 

We also appreciate the reviewer’s comments regarding the professional language editing of the article. We have carefully addressed these points and made the necessary revisions.

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

In the peer-reviewed manuscript ‘Climate Change of Near-Surface Temperature in South Africa Based on Weather Station Data, ERA5 Reanalysis, and CMIP6 Models’ by I. Serykh et al. Serykh et al. describe changes in surface air temperature in the region of South Africa.

The paper is written in clear scientific language, is well structured, and is a comprehensive and accessible piece of work for a wide audience. The issues studied are of interest to the research region and to those seeking to expand their knowledge of the impact of climate change on ecosystems of different scales.

The introduction contains sufficient background information and demonstrates the authors' good awareness of the issue under study. The 'Materials and Methods' section is described in sufficient detail and does not raise any further questions. The authors have clearly put in a lot of work to collect and process a large amount of data. This data has been processed using modern methods. The conclusions drawn by the authors are consistent with the results obtained.

Some comments:

It is necessary to clarify in the captions of Tables 1 and 3 what the underlined data means.

Fig. 3 needs the ordinate axis to be labelled.

Fig. 4 and 5 need the axes labelled.

Literature source 26 is not available or present. Please correct the reference or replace the literature.

Literature source 38 is from 2013; the current version was released in 2021. Please supplement the literature list with a more up-to-date version.

In my opinion, the manuscript can be published once these minor corrections have been made.

Author Response

Answer to Reviewer 4

Some comments:

Comment 1: It is necessary to clarify in the captions of Tables 1 and 3 what the underlined data means.

Response 1: The text has been amended accordingly. In Table 1, all underlining and bolding have been removed. And in Table 3 (now its Table 5), a note has been added.

Comment 2: Fig. 3 needs the ordinate axis to be labelled.

Response 2: Corrected. The ordinate axis of Fig. 3 is marked - these are degrees Celsius.

 

Comment 3: Fig. 4 and 5 need the axes labelled.

Response 3: Corrected. The axes of Fig. 4 and 5 are marked - these are degrees Celsius.

 

Comment 4: Literature source 26 is not available or present. Please correct the reference or replace the literature.

Response 4: We checked the link. It is now available.

 

Comment 5: Literature source 38 is from 2013; the current version was released in 2021. Please supplement the literature list with a more up-to-date version.

Response 5: The link to the IPCC 2021 report is in the manuscript. Its number is 40.

Author Response File: Author Response.docx