Differences of East Asian Summer Monsoon Precipitation Responses between Transient and Stabilization Simulations

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors The study points to the response of East Asian Summer Monsoon precipitation to global warming targets (1.5 and 2.0 degrees Celsius). The manuscript discusses the role of thermodynamic and dynamic responses to precipitation changes over the East Asian Monsoon region via two different greenhouse gas emission pathways. 

 

The manuscript is relevant to the field and provides a quantitative explanation of the changes in precipitation over East Asia during the monsoon season rather than qualitative assessments. Please add your research questions and the novelty of your research in the introduction section.
According to the present study, the East Asian Subtropical Jet (EASJ), its position, and its intensity in transient and stabilization experiments determine the vertical motion and the corresponding changes in circulation patterns. Previous studies have linked the precipitation variability to the changes in West North Pacific Subtropical High.
 The methodology is not novel since previous studies have used similar diagnostic approaches to find solutions for their research questions. Regarding the model experiments, the authors have used the already available CESM simulations on the NCAR website. However, the authors can mention a similar study based on different models or multimodel ensembles in their future work section. (Since the present study involves only one model, CESM). Additionally, they could explain how the result of the present study helps in regional climate risk assessments and potential adaptation strategies.
The illustrations are of high quality. In the conclusion section, I suggest the authors represent the mechanism for the two pathways leading to differences in EASM precipitation as a schematic that involves the role of EASJ.

Author Response

We would like to thank the reviewer for his/her helpful comments on our manuscript. We believe it is now better after addressing the reviewer's concerns. We provide our point-by-point responses (in the bulleted Roman text) to comments and issues raised (in italics text).

The study points to the response of East Asian Summer Monsoon precipitation to global warming targets (1.5 and 2.0 degrees Celsius). The manuscript discusses the role of thermodynamic and dynamic responses to precipitation changes over the East Asian Monsoon region via two different greenhouse gas emission pathways.

The manuscript is relevant to the field and provides a quantitative explanation of the changes in precipitation over East Asia during the monsoon season rather than qualitative assessments. Please add your research questions and the novelty of your research in the introduction section.

Response:

• Thank you for this suggestion. We have added more description about our research questions and the novelty in the Introduction section (lines 86-93 of the revised manuscript).

 

According to the present study, the East Asian Subtropical Jet (EASJ), its position, and its intensity in transient and stabilization experiments determine the vertical motion and the corresponding changes in circulation patterns. Previous studies have linked the precipitation variability to the changes in West North Pacific Subtropical High.

The methodology is not novel since previous studies have used similar diagnostic approaches to find solutions for their research questions. Regarding the model experiments, the authors have used the already available CESM simulations on the NCAR website. However, the authors can mention a similar study based on different models or multimodel ensembles in their future work section. (Since the present study involves only one model, CESM). Additionally, they could explain how the result of the present study helps in regional climate risk assessments and potential adaptation strategies.

Response:

• Thank you for this suggestion. We have complemented the meaning of the research in regional climate risk assessments and potential adaptation strategies (lines 337-341 of the revised manuscript).
• We follow the reviewer’s suggestion to mention a similar future study based on multimodel ensembles(lines 346-354 of the revised manuscript).

 

The illustrations are of high quality. In the conclusion section, I suggest the authors represent the mechanism for the two pathways leading to differences in EASM precipitation as a schematic that involves the role of EASJ.

Response:

• Thank you for your recognition of our illustrations. However, an accurate and vivid schematic illustration is still a big challenge for us, especially within the tight revision time limit. So, we are sorry that we could not provide one.

Reviewer 2 Report

Comments and Suggestions for Authors

Manuscript title: “ Differences of East Asian summer monsoon precipitation responses between transient and stabilization simulations".

The main queries are listed below:

1. Manuscript doesn’t have page and line number and makes it difficult for reviewing.

2. Abstract is not prepared in a scientific structure and needs to modify. The time period and location of the study is missed. Adding some parts of “Material & Methods- measuring methods” and quantified “results” is necessary for improving it.

3. In first time, the abbreviations should be completely described (for example, CESM in abstract).

4. Different font size is used in the manuscript and should be corrected.

5. In equations 1 to 4, what did you consider for upper limitations boundary? What did you replace for “surface”?

6. Figures: the legend should have reasonable units and all parts should described carefully.

7. As a main part of your results are presented in Figures, how do you validate your results? It is a main challenge in your study.

8. Unfortunately, no comparisons are made between the results of this research and those of similar works. I can also suggest that the author(s) invest their efforts in discussing the results and their possible reasons.

Author Response

We would like to thank the reviewer for his/her helpful comments on our manuscript. We believe it is now better after addressing the reviewer's concerns. We provide our point-by-point responses (in the bulleted Roman text) to comments and issues raised (in italics text).

1. Manuscript doesn’t have page and line number and makes it difficult for reviewing.

Response:

• We are very sorry about this point and we have added line numbers in the revised manuscript.

 

2. Abstract is not prepared in a scientific structure and needs to modify. The time period and location of the study is missed. Adding some parts of “Material & Methods- measuring methods” and quantified “results” is necessary for improving it.

Response:

• Thank you for this suggestion. Transient 1.5°C and 2°C warming levels are taken as the time slices that 30-year global mean surface temperature (GMST) reaches 1.5°C and 2°C above pre-industrial levels for the first time. The time periods are not exactly the same in different ensembles. On average, GMST reaches transient global warming of 1.5°C and 2°C during 2015–2044 (centers at 2029) and 2027–2056 (centers at 2041), respectively. We have added more description about it (lines 135-137 of the revised manuscript).
• Stabilized 1.5°C and 2°C warming levels are the last 30-year time slices in the 21st century, which is 2071– We have added more description about it (line 138 of the revised manuscript).
• The East Asian summer monsoon (EASM) region is defined as the area covering 100°E-150°E; 20°N-50°N in this study. We have added a covering range the first time we mentioned it in the Introduction section (lines 35-36 of the revised manuscript).

 

3. In first time, the abbreviations should be completely described (for example, CESM in abstract).

Response:

• Thank you for this suggestion. We have checked all abbreviations and fixed this issue.

 

4. Different font size is used in the manuscript and should be corrected.

Response:

• Thank you for this suggestion. We have fixed this problem.

 

5. In equations 1 to 4, what did you consider for upper limitations boundary? What did you replace for “surface”?

Response:

• In this study, we follow the previous research (e.g., Seager et al. 2010; Qu et al. 2014; Lee et al. 2018), and the upper limitation is 100hPa. The model output has the variable, surface pressure, which refers to as the surface. We have added more descriptions about it (lines 149-150 of the revised manuscript).

 

• Lee, D., S.-K. Min, E. Fischer, H. Shiogama, I. Bethke, L. Lierhammer, and J. F. Scinocca, 2018: Impacts of half a degree additional warming on the Asian summer monsoon rainfall characteristics. Environ. Res. Lett., 13, 044033,https://doi.org/10.1088/1748-9326/aab55d.
• Qu, X., G. Huang, and W. Zhou, 2014: Consistent responses of East Asian summer mean rainfall to global warming in CMIP5 simulations. Theor.Appl. Climatol., 117, 123-131, https://doi.org/10.1007/s00704-013-0995-9.
• Seager, R., N. Naik, and G. A. Vecchi, 2010: Thermodynamic and dynamic mechanisms for large-scale changes in the hydrological cycle in response to global warming. J.Climate, 23, 4651-4668, https://doi.org/10.1175/2010JCLI3655.1.

 

 

6. Figures: the legend should have reasonable units and all parts should described carefully.

Response:

• Thank you for this suggestion. In our figures, only Figure 4 has the legend and the arrow in the meridional and vertical direction denotes 0.5m/s and 0.5*(-10^-2 Pa/s), respectively. It is hard to add the units to the legend. Hence, we described it carefully in the annotation (lines 486-487 of the revised manuscript).

 

7. As a main part of your results are presented in Figures, how do you validate your results? It is a main challenge in your study.

Response:

• When we project the future climate, state-of-the-art earth system models (ESMs) are usually the only tool we can take. Their ability to simulate climate is evaluated during the historical time period. We could trust CESM only by its historical performance.

 

8. Unfortunately, no comparisons are made between the results of this research and those of similar works. I can also suggest that the author(s) invest their efforts in discussing the results and their possible reasons.

Response:

• Thank you for this suggestion. Previously, research was largely carried out based on transient simulations, and few studies utilized stabilization simulations only. Our research exposes the considerable differences in the most important regional weather and climate system in East Asia, i.e. the EASM system, between transient and stabilization responses. Specifically, southern China would be exposed to more severe extreme precipitation and flood risk in stabilization responses. It was largely underestimated in research based on traditionally transient We have added more discussion (lines 337-341 of the revised manuscript).

 

Reviewer 3 Report

Comments and Suggestions for Authors

I have reviewed the manuscript entitled “Differences of East Asian summer monsoon precipitation responses between transient and stabilization simulations”. In this paper, the authors have examined the two global warming targets of the Paris Agreement, 1.5 °C and 2 °C above pre-industrial levels. It is very intriguing to have such thoughts on comparison which has no relevance. That way there can be many comparisons. I don’t agree with the scientific question itself. I do not recommend this manuscript for publication.

 

 

Comments on the Quality of English Language

 Moderate editing of the English language required

Author Response

We feel sorry that the reviewer cannot recognize the meaning of our research. However, we believe our work could facilitate a better understanding of the EASM responses in different scenarios.

In its decision on the adoption of the Paris Agreement, the Conference of Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) at its 21st Session in Paris, France (30 November to 11 December 2015), invited the IPCC to provide a special report (Hoegh-Guldberg et al. 2018) in 2018 on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways.

The broad scientific community has responded to the UNFCCC invitation. The Special Report (Hoegh-Guldberg et al. 2018) is an assessment of the relevant state of knowledge, based on the scientific and technical literature available and accepted for publication up to 15 May 2018. The Report draws on the findings of more than 6,000 published articles.

A major challenge in assessing climate change under 1.5°C, or 2°C (and higher levels), of global warming pertains to the definition of a ‘1.5°C or 2°C climate projection’ (Hoegh-Guldberg et al. 2018). The Special Report clearly pointed out that it is necessary to distinguish between transient and stabilization climate responses. These responses can be very different in terms of climate variables and the inertia associated with a given climate forcing.

The Special Report inspired us to conceive of this research and we believe our work could facilitate a better understanding of the problem.

 

• Hoegh-Guldberg, O., and Coauthors, 2018: Impacts of 1.5ºC Global Warming on Natural and Human Systems. Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty, Masson-Delmotte, et al., Eds., In Press, 183-186.

Reviewer 4 Report

Comments and Suggestions for Authors

I read the manuscript entitled ‘Differences of East Asian summer monsoon precipitation responses between transient and stabilization simulations’ with interest. In the article, the authors distinguish between two simulated types of East Asian summer wind (EASM) responses, transient and steady, based on a fully coupled CESM model with a low warming target. The results reveal a great difference between transient and steady responses of the most important regional weather and climate system in East Asia, i.e., the EASM system. However, it is considered that the paper needs to be improved and some additional experiments are needed which may help to make the manuscript more acceptable to the readers.

1. The article mentions that regional differences in climate response may affect local capacity to cope with climate change. Further discussion of the actual impacts that these differences may have on local societies, agriculture and economies, as well as policies and strategies to address climate change, would make the study more relevant.

2. The references to the key roles of EASJ and upper level circulation are good, but more detailed explanations are needed to clearly show how they affect the EASM response.

3. Highlight how your research contributes to filling gaps in knowledge or providing new insights from previous research.

4. It was suggested that some data from the previous two years be added to the article.

5. While the study presents the idea of an in-depth study of the EASM response, the article does not explicitly mention specific novel theories or methods to move research in this area forward. In terms of innovation, more new data sources, new analytical techniques, or interdisciplinary approaches could be explored to gain insight into EASM response.

Comments on the Quality of English Language

Extensive editing of English language required.

Author Response

We would like to thank the reviewer for his/her helpful comments on our manuscript. We believe it is now better after addressing the reviewer's concerns. We provide our point-by-point responses (in the bulleted Roman text) to comments and issues raised (in italics text).

1. The article mentions that regional differences in climate response may affect local capacity to cope with climate change. Further discussion of the actual impacts that these differences may have on local societies, agriculture and economies, as well as policies and strategies to address climate change, would make the study more relevant.

Response:

• Thank you for this suggestion. In this study, our results focus on the responses of the East Asia summer monsoon, which is one of the most important climate systems in East Asian regions. Following the reviewer’s suggestion, we have added more discussion of differences that may have on local societies, agriculture, and economies in the Summary and discussions section (lines 340-341 of the revised manuscript).

 

2. The references to the key roles of EASJ and upper level circulation are good, but more detailed explanations are needed to clearly show how they affect the EASM response.

Response:

• Thank you for this suggestion. We have cited more references to explain how the EASJ affects the EASM response, in a more detailed way (lines 233-237 of the revised manuscript).

 

3. Highlight how your research contributes to filling gaps in knowledge or providing new insights from previous research.

Response:

• Thank you for this suggestion. Previously, research was largely carried out based on transient simulations, and few studies utilized stabilization simulations only. Our research exposes the considerable differences in the most important regional weather and climate system in East Asia, i.e. the EASM system, between transient and stabilization responses. Specifically, southern China would be exposed to more severe extreme precipitation and flood risk in stabilization responses. It was largely underestimated in research based on traditionally transient We have added more description about it (lines 335-339 of the revised manuscript).

 

4. It was suggested that some data from the previous two years be added to the article.

Response:

• Thank you for this suggestion. We have mentioned the Coupled Model Intercomparison Project Phase 6 (CMIP6) output, especially the Scenario Model Intercomparison Project (ScenarioMIP) within it, and our future work could apply ScenarioMIP output and provide more comprehensive results (lines 347-354 of the revised manuscript).

 

5. While the study presents the idea of an in-depth study of the EASM response, the article does not explicitly mention specific novel theories or methods to move research in this area forward. In terms of innovation, more new data sources, new analytical techniques, or interdisciplinary approaches could be explored to gain insight into EASM response.

Response:

In its decision on the adoption of the Paris Agreement, the Conference of Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) at its 21st Session in Paris, France (30 November to 11 December 2015), invited the IPCC to provide a special report (Hoegh-Guldberg et al. 2018) in 2018 on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways. A major challenge in assessing climate change under 1.5°C, or 2°C (and higher levels), of global warming pertains to the definition of a ‘1.5°C or 2°C climate projection’ (Hoegh-Guldberg et al. 2018). The Special Report clearly pointed out that it is necessary to distinguish between transient and stabilization climate responses.

The Special Report inspired us to conceive of this research and we believe our work could facilitate a better understanding of the problem. Our major novelty is our approach which uses both transient and stabilization simulations to investigate the EASM and make the comparisons with appropriate methods.

 

• Hoegh-Guldberg, O., and Coauthors, 2018: Impacts of 1.5ºC Global Warming on Natural and Human Systems. Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty,Masson-Delmotte, et al., Eds., In Press, 183-186.

 

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

 I recommend submitting the present form as the author has addressed all of my inquiries.

Comments on the Quality of English Language

Minor editing of English language required

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have more fully revised the first round of recommendations.

Comments on the Quality of English Language

Moderate editing of English language required.