High-Rate Precipitation Occurrence Modulated by Solar Wind High-Speed Streams
Round 1
Reviewer 1 Report
In this work, authors discuss the association between severe weather events, e.g. heavy rainfalls and flash floods, and solar/interplanetary disturbances affecting the magnetosphere-ionosphere-atmosphere system.
In the first part of this work the authors focus on three different cases of severe weather events occurred in Japan, Australia and US. This leads to a statistical analysis over extended time periods confirming the previous observations through the superposed epoch technique. The main result is the observed modulation of heavy rainfall time series in response to changing interplanetary conditions. Indeed, periodic modulations associated with solar rotation period of ~27 day and higher harmonics of ~13.5 day and ~9 are observed in the heavy rainfall data.
In the second part authors discuss the mechanisms that connect the solar wind driver to the modulation observed in the atmospheric circulation, related to the severe weather events considered in the study, i.e. the auroral heating due to the coupling between the solar wind and magnetosphere-ionosphere-atmosphere system produces heating in the troposphere that can originate gravity waves. Among three different case studies reported, the 2015 July 4-5 event is analyzed in detail through ground-based magnetic field observations, convective cell images and gridded daily precipitation data.
In my opinion the work is detailed, well organized with fair references and offers significant results which are fully within the scope of the journal. Only minor revisions are needed according to the specific corrections/comments that follows in the report.
A general remark: the quality of the Figures is quite poor and it could be difficult to properly read them in the present form, especially those with many small subplots. An increase in their resolution would be recommended in order to make them more readable!
- Specific comments:
Figure 2: I suggest to add the maximum rainfall (crosses) in the caption for sake of clarity.
Line 241: The acronym "HCS plasma sheet" already contains the word "sheet", thus remove it.
Section 5: in this section the aim of the SPE analysis is to highlight the tendency of heavy rainfall/flash flood events to follow the arrival of HSS/CIR at the Earth, by setting the reference key-time according to the arrival time of the solar wind disturbance. HSSs are selected with different thresholds in the analysis showed for Japan, V_max > 700 km/s, Australia, V_max > 500 km/s and US, V_max > 600 km/s over the considered period 1998-2019. Moreover, the results of heavy precipitations with/without typhoons (Japan), cyclones (Australia) and hurricanes (US) are calculated with V_max > 650, V_max > 550 and V_max > 400, respectively. There is a specific reason for all these different V_max values? Please clarify.
Line 505: Typo: "histograms peak" --> "histogram peak"
Line 573: Write only "Figure 1c" instead of "as already discussed in Section 3 (Figure 1c)", as the same phrase is written at the beginning of the paragraph already.
Line 625: There is an extra dot, please remove it.
Line 607: In the caption of Figure 8 authors introduce the "cumulative numbers of HCS crossings", is this the number of HCS crossings per day? Please explain in the text.
Line 729: Same of line 607
Line 746: In the caption of Figure 11 use the acronym for HCS introduced above.
Line 949: "HSS that arrived on July 10" --> "HSS that arrived on August 10"
Line 952: "In contrast, it was on July 10" --> "In contrast, it was on August 10"
Line 954: "Also, on July 17" --> "Also, on August 17"
Figure 15: The figure cannot be read properly in the present form. Indeed, the tiny panels on top of 15a and 15b are not visible. Please correct "NAL" in the legend of panel (b), since the signal reported in black corresponds to the detrended timeseries of the x-magnetic field component observed at Sørøya.
Author Response
A general remark: the quality of the Figures is quite poor and it could be difficult to properly read them in the present form, especially those with many small subplots. An increase in their resolution would be recommended in order to make them more readable!
Reply: Thank you for careful reading and corrections.
The reason for poor quality of the Figures is how the high-resolution .eps files were inserted into Word document. This is now fixed. All final Figures have been submitted in hi-res .eps format.
- Specific comments:
Figure 2: I suggest to add the maximum rainfall (crosses) in the caption for sake of clarity.
Reply: Figure caption amended.
Line 241: The acronym "HCS plasma sheet" already contains the word "sheet", thus remove it.
Reply: Removed.
Section 5: in this section the aim of the SPE analysis is to highlight the tendency of heavy rainfall/flash flood events to follow the arrival of HSS/CIR at the Earth, by setting the reference key-time according to the arrival time of the solar wind disturbance. HSSs are selected with different thresholds in the analysis showed for Japan, V_max > 700 km/s, Australia, V_max > 500 km/s and US, V_max > 600 km/s over the considered period 1998-2019. Moreover, the results of heavy precipitations with/without typhoons (Japan), cyclones (Australia) and hurricanes (US) are calculated with V_max > 650, V_max > 550 and V_max > 400, respectively. There is a specific reason for all these different V_max values? Please clarify.
Reply: Clarification sentences added.
Line 505: Typo: "histograms peak" --> "histogram peak"
Line 573: Write only "Figure 1c" instead of "as already discussed in Section 3 (Figure 1c)", as the same phrase is written at the beginning of the paragraph already.
Reply: Done.
Line 625: There is an extra dot, please remove it.
Line 607: In the caption of Figure 8 authors introduce the "cumulative numbers of HCS crossings", is this the number of HCS crossings per day? Please explain in the text.
Reply: Yes, cumulative number of HCS crossings per epoch day. Explained in the text/
Line 729: Same of line 607
Line 746: In the caption of Figure 11 use the acronym for HCS introduced above.
Line 949: "HSS that arrived on July 10" --> "HSS that arrived on August 10"
Reply: N/A - Section removed.
Line 952: "In contrast, it was on July 10" --> "In contrast, it was on August 10"
Reply: N/A - Section removed.
Line 954: "Also, on July 17" --> "Also, on August 17"
Reply: N/A - Section removed.
Figure 15: The figure cannot be read properly in the present form. Indeed, the tiny panels on top of 15a and 15b are not visible. Please correct "NAL" in the legend of panel (b), since the signal reported in black corresponds to the detrended timeseries of the x-magnetic field component observed at Sørøya.
Reply: N/A - Section removed.
Reviewer 2 Report
Dear authors,
Please, find attached my comments
Best regards
Comments for author File: 
Comments.pdf
Author Response
General comments
The manuscript presents a very deep analysis of the relationship between solar wind activity and heavy rainfall events.
The main issue of the document is the length of itself. Although I have not found any consideration about this in the guidelines, the 44 pages and 170 references are clearly over the mean values of the manuscripts accepted in the journal. My suggestion is to divide the document into two parts, or, on the opposite, reduce the length considerably.
Reply: Agree. Initially we considered submitting in two parts but the guidelines for this Special Issue do recommend it, although there is no page limit stated. We have removed the original Section 6 from this manuscript.
The number of data sources is too much large, section 2 is not clear at the time of explaining why the authors need such several variables, and how they will be combined.
Reply: The number of data sources is now somewhat reduced, but they are needed to cover three geographic areas. Regarding the solar wind data, this limited number of variables is needed to characterize HSS/CIRs, as briefly explained in this section and the reader is referred to previous publications for further details if needed.
Figures have a very poor resolution and they are improved.
Reply: The reason for poor quality of the Figures is how the high-resolution .eps files were inserted into Word document. This is now fixed. All final Figures have been submitted in hi-res .eps format.
I have doubts about the entire Section 3: What is the intention of the authors in these 6 pages? To present the motivation of your research? If the answer is affirmative, please indicate at the beginning of the section and reduce notably the length. This section should be moved just after the introduction because is not part of the authors’ work.
Reply: Section 3 is meant not only to highlight the motivation of this research but, we believe, it is beneficial for understanding the characteristics of solar wind, the MIA coupling and its potential global impact on tropospheric weather as previously discussed. Furthermore, it prepares the ground for the SPE analysis used in the subsequent sections. It cannot be moved just after the Introduction because it is part of this study and uses the data described in Section 2. A description of each section is provided in the introduction.
The methodology used in section 4 is not presented in any part of the work. Please note that the reader of the journal needs to have the maximum information about each part of your analysis.
Reply: A paragraph is added to explain the use of the superposed epoch analysis method in this manuscript.
It results impossible to me to follow your deductions about the results, e.g. in section 4.
Reply: Hopefully the added paragraph above helps before reading Section 4 and 5.
Sections 4 and 5 should be merged and retailed, focusing on the main points of your analysis.
Reply: As explained in the added paragraph, and at the beginning of these sections, the SPE analysis in these sections use different key times, which is the main reason for the separation in two sections.
Section 6 is another manuscript and should be removed from this document.
Reply: This part of the manuscript is removed and replaced by a short new Section 6. Discussion
Conclusions do not reproduce all the results presented in your analysis.
Reply: Conclusions of the revised manuscript now focus on the results of the analysis.
You should consider focusing on how to conduct your research to answer the points indicated in this last section.
As it has been cited before, the number of references is extremely long and should be reduced. For sure, removing parts of the text will be an exercise that can help to minimize the length of the considered externals works.
Reply: Done. Thank you.
Specific comments
Abstract: “it is shown that precipitation occurrence is modulated by solar wind high-speed streams.” This is part of your research, or it is based on the literature? Could you specify, please?
Reply: This is part of the research presented in this manuscript.
L17: When you refer to severe weather are you considering tornadoes, large hail or extreme convective winds (downbursts, and other straight winds associated with convection)? Please, clarify
Reply: The adjective ‘severe’ is removed in the abstract. This manuscript is concerned with heavy precipitation events leading to floods, caused by deep convection and intensification of extratropical cyclones in general. This is clarified in the revised Introduction. Tornadic cells, large hail and other specific convective phenomena are beyond the scope of this study. After removing the original Section 6 the convection is not addressed other than discussed in the new Section 6.
Reply: According to other separations between paragraphs, please an empty line in L43
L44: Please, if the “Wilcox” effect is not a result of your research, please should present in the introduction
Reply: The “Wilcox” effect is introduced in the introduction and the similarity of the results of our research to the Wilcox effect are discussed in Section 6.
A presentation of the different sections of your manuscript is desired at the end of the Introduction section.
Reply: A summary of each section is provided in the introduction.
L610: Which is the reason of “We now extend the SPE analysis to a time interval of ±36 days from the arrival time of major HSSs/CIRs”?
Reply: The reason (to show examine the influence of recurrent HSS/CIRs) is stated (avoiding the first person sentence structure).
L937: “We now examine these four weather…” I suggest not using the first person along with the analysis
Reply: Done. Thank you.
Reviewer 3 Report
The paper titled “High-rate precipitation occurrence modulated by solar wind high-speed streams” deals with the extreme weather events.
In particular, the focus is on rainfall that causes flooding, and flash floods continue to present difficult challenges in forecasting. The authors analyze and propose different approach on this scope.
The subject matter is within the scope of the journal and in terms of originality, subject coverage, clarity of presentation, strength of data and importance in field the paper is excellent. The title accurately reflects the content, the language is correct and the abstract is adequate.
The only remark to be taken into account is that the figures could be improved. After these minor revisions, the paper should be accepted for publication.
Author Response
The subject matter is within the scope of the journal and in terms of originality, subject coverage, clarity of presentation, strength of data and importance in field the paper is excellent. The title accurately reflects the content, the language is correct and the abstract is adequate.
The only remark to be taken into account is that the figures could be improved. After these minor revisions, the paper should be accepted for publication.
Reply: Thank you. The reason for poor quality of the Figures is how the high-resolution .eps files were inserted into Word document. This is now fixed. All final Figures have been submitted in hi-res .eps format.
Round 2
Reviewer 2 Report
Dear authors,
I would like to congrats you on the effort made for improving your manuscript. I think that the readability is quite good now, but there are some points that, from the point of view of the reader, you should attempt to make them more clear.
Please, find attached my report.
Best regards.
Comments for author File: Comments.pdf
Author Response
General comments
The authors present an interesting manuscript regarding the relationship between solar wind activity and heavy rainfall occurrence. The document is well-conducted, and it has been improved after first review. Besides, the quality of the figures, one of the major issues detected before, has been improved in the right sense. However, there are some issues that the authors should improve to make the manuscript acceptable for the journal.
The first one continues being the length. Although the document has been reduced notably, and I would like to thank the authors the effort for doing the exercise, it continues being excessively long. This is a major issue, in the sense that it reduces the interest of the reader on the very interesting research. I provide some suggestions that could guide the authors in this sense:
- Do you think that do you need all the data sources included in section 2? In the case of a negative answer, please focus only on those that could explain the main part of your research. If the answer is yes, then I suggest reducing the content of all the paragraphs letting only the main points. You should note that it results difficult to the reader to have in mind all the parameters presented, and my proposal is removing all that give a residual information. This point has a link with the next one.
Reply: Thank you for very helpful comments and suggestions. Section 2 is now shortened by removing APHRODITE data set, which also resulted in removal of Fig. 4. Other paragraphs are also slightly shortened. We could have avoided some data descriptions by referencing our previous publications, but that would be unfair to readers having to search for that information themselves.
- Because section 3 is only providing a motivation of your research, I suggest reducing notably the three sub-sections. There is a lot of information in this section, making that the reader has difficult for focusing on the message that the authors want to give, which I assume that in all the presented cases of extreme weather the solar activity shows a particular characteristic. Then, I have two options, that maybe the authors could even combine: first, reduce the paragraphs’ length, and merge them. The second proposal is to make a table with the main points of the three presented cases.
Reply: Section 3 is now reduced to the content of 3.1, with 3.2 and 3.3 removed.
As explained in the Introduction, section 3 is meant not only to provide a motivation of your research. Therefore, we retain it but focus on Japan.
- To give a large weight to the main point of your research, that if I have understand right is the subsection 5.4, I propose the authors again summarize the sub-sections 5.1, 5.2 and 5.3 in a unique one, presenting only the most clear example (you do not need to show the cases for all the studies), and a table with the secondary results that you need to show to the reader.
Reply: Section 5 was structured because it deals with 3 different geographic regions. While this makes logical sense, the sub-sections are rather short so they are now combined into one sub-section 5.1, followed by sub-section 5.2.
Minor comments
L238-240: Be careful with these lines because they are indicating an opposite result that what you want to show. If you have found one or more cases that are not in accordance with your hypothesis, you must mention but indicating that more research should done in this sense or that the solar activity is not the main ingredient and heavy rain can occur in other conditions. Maybe you also should propose a statistical analysis of some skill scores (POD, FAR, CSI…) that could help to understand the influence of the main point of your research.
Reply: In the last paragraph of Section 3 we further elaborate on these lines. The idea of “statistical analysis of some skill scores” sounds interesting but seems to be beyond the scope of this paper and our present understanding of skill scores (POD?, FAR?).
Please, explain why “Events caused by typhoons are excluded.” (L416)
Reply: Justification for excluding typhoons is now given in Section 4, 2nd paragraph.
Could you present fig. 4 horizontally?
Figures 4 and following: you can use in the caption the form, “Same that fig. 3 but for the case of …”
Reply: N/A (figure 4 removed) However, there is no need to present figures like this horizontally, because they fit neatly into columns when typeset in published papers. Besides, the vertical presentation of these figures shows the SPE results lined up relative to the key time.
