Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

 

This paper presents a comprehensive study on the CME forecasting methods. The forecasting results were compared with interplanetary CME (ICME) catalogs, showing that the system predicted 189 out of 280 events (68%) within a tolerance of 48 hours, indicating the performance of the method. The work is contributive to the community and fits the journal well, I recommend publishing after addressing following concerns.

 

1. Is the method open-source or is there plans to publish the source code of the method, this should be indicated in the paper

2. The method would be more conveniencing if the author can provide one selected example including (but not limited to), observations (coronal holes), model processed results (ambient solar wind speed), prediction compared with in-situ.

3. Comparison only provided in SMDC with WSA-Enlil+Cone model in Sectoin 3. I would suggest the author to consider comparing with more recent models ([1]ELEvo Strong coronal channelling and interplanetary evolution of a solar storm up to Earth and Mars, [2] EUHFORIA [3]Predicting Solar Wind Streams from the Inner-Heliosphere to Earth via Shifted Operator Inference)

Comments on the Quality of English Language

Quality of English is good in general

Author Response

 

The authors would like to express their gratitude to the reviewer for the interesting comments and valuable recommendations. 

Comment 1: Is the method open-source or is there plans to publish the source code of the method, this should be indicated in the paper

Response 1: We do not have plans to publish the source code of the method at the moment. However, we support openness and transparency in scientific research, and will consider open sourcing of the method or some parts of the method in the future. Thank you for the idea.

 

Comment 2: The method would be more conveniencing if the author can provide one selected example including (but not limited to), observations (coronal holes), model processed results (ambient solar wind speed), prediction compared with in-situ.

Response 2: Thank you for the recommendation. We agree that such example could better demonstrate our approach and added the new subsection in the Results section (3.5, Lines 543-587) that contains a detailed example.

 

Comment 3: Comparison only provided in SMDC with WSA-Enlil+Cone model in Sectoin 3. I would suggest the author to consider comparing with more recent models ([1]ELEvo Strong coronal channelling and interplanetary evolution of a solar storm up to Earth and Mars, [2] EUHFORIA [3]Predicting Solar Wind Streams from the Inner-Heliosphere to Earth via Shifted Operator Inference)

Response 3: The method described in the paper is intended to be used online, and uses input data that is available in real-time. The WSA-Enlil+Cone model also operates online and published hit/miss/false alarm statistics for the same period that considered in our paper. We have added an example of the forecast of the event that occurred 2014-01-07, as described in the article (about ELEvo) you mentioned, and compared the results of that forecast with other models listed in the CCMC CME Scoreboard (see Table 8).

 

Reviewer 2 Report

Comments and Suggestions for Authors

General opinion: this paper is quite difficult to read until the end, even though near field researchers like me.  Therefore, I propose you to cut extra unnecessary parts of explanation, especially described in Introduction. You had better present essential parts of this paper by the graphs (Table 4).  Furthermore it is necessary to make the Abbreviations corner, since you use so many abbreviations in the paper.  Therefore for readers, it makes hard to follow your logic (avoid lost of logic).

 

1. One of the most drastic change, I require you, is to connect from line 48 to line 154. Cut between line 49 and 153.  Make short introduction, otherwise your works will lose the focus.

2.  The line 41 -43, you provided some results of your work, but this results give quite strange impression to me.  Why?  You have only provided error bars and standard deviations, but not provided the mean value (average value). This makes difficult to understand straightforwardly what you have done.

3.  I had trouble to understand the term; the “drag-based” model. I read another paper that you have referred in your paper and understand it (by T. Zic et al).  Online 229, there are plus term and minus term.  Plus is pushing force from behind by the fast solar wind and minus means the drag by the collision. However according to your list of CME from the paper that you have published in “Cosmic Research” (2021) in Table 1, the average velocity of CME is around 400 km/s. Is it nearly the same speed of the solar wind?  Therefore it is not so dominant effect on CME that acts the drag force or pushing by the solar wind?

4.  I have a question on your formalism on line 199.  The CME speed depends on “constant term + corona hole area”.  Is it true?  I thought high speed solar wind is frequently observed from the Solar Polar Regions.  I should check it to solar wind specialist. But don’t you put the difference of high speed solar wind and low speed solar wind into your analysis (also the latitude parameter)?

5.  Line 244. You have only mentioned the drag effect, but is there no effect from the pushing effect (acceleration) by the solar wind?

6.  Section 2.4 “event selection”.  This part is easier to read.  So for paper writing, the main focus should be given on these contents.

7.  Line 269.  Why 240-300 degrees corresponds to the equatorial CME?  Is it .120-240 degrees?

8.  Line 272. CME-dimming should be “CME dimming event”.  There are plenty of this word (dimming) in this paper.  Please check them by yourself.  It is quite hard what it relates with the real coronagraph image.

9.  Line 292.  What does off-limb events point out?? Please include more detail explanation on this, for example, in the table caption of Table 1.

10.  Line 302.  What do you mean “narrow events filter”?  Slightly detail explanation should be added.

11.  Line 347-349. There need three pictures for each case.

12.  Line 351-362.  It is difficult to understand what you want to say here.

13.  Line 262.  I can access the first page of your web site, but I cannot enter in each column in your web site.

14.  I propose you to insert new sub session like “2.5 list making process”.

Because your explanation try to explain different subject from line 255 to 330.

It would make easier for readers to understand what you would like to say here.

15.  Line 373-374. The weak CME will make the geomagnetic events?  From a point of view of space weather? Line 375 to 379, it is interesting!

 

On Table 4, I strongly recommend to present the results on the figures. Like Figure 5 of your paper “Cosmic Research” in 2021.  In the graph of Cosmic Research, the center of the horizontal axis is set at 0 hours.  I suggest you to replace 0 to actual average hour and one more graph actual average velocity.   Please make two figures for the arrival time (TOA distribution) and average velocity. Then the 2day, one day parameters would be much more easily understood.  Table 5, also the same.  Figure is better.

 

16.  Line 394. TAO should be TOA. Simple typing mistake. Typo.

17.  Line 460-461.  Is it better to add new sub session like “3.2 comparison with other works….”

18.  Line 464-479.  Please specify your work and the other works more clearly. Line 484-485, I can understand that this is your work.  Like that.

19.  Line 490-491.  It may be a conclusion.

20.  Line 515. -58.1 km.  This is in Major disturbances, a high speed CME is involved.  One of the example may be 2004.11.6-7 event.  The CME run with high speed exactly 1,000km/sec in 1AU.

21.  Line 517-520.  I agree this descriptions.

22.  Line 524-547.  From the space weather forecast point of view, these contents may be not essential.

23.  Line 549. Results of the Moscow State University Space weather Monitoring Data Center.  It would be better to put full spelling here.

Also for CACTus à Computer Aided CME tracking software.

24.  Line 564-586. Dimming à Dimming “events”. Lines 564, 575, 577, 580, 584, 586, 591.  The same modifications

 (addition)are necessary.

25.  Line 590.  What is the 2D DBM simulation?  Two dimensional simulation?  .

26 .  Line 591-592.  I agree this interpretation.

27.  Line 602-606.  I agree with this conclusion.

Comments on the Quality of English Language

This paper is very difficult to read. It is not a problem with the English language. But it arises from the stream of English logic. 

Author Response

 

The authors are grateful to the reviewer for useful recommendations and interesting discussion. Your insights have significantly enhanced the quality of our article. We appreciate the time and effort you put into your review.

Comment 1: One of the most drastic change, I require you, is to connect from line 48 to line 154. Cut between line 49 and 153.  Make short introduction, otherwise your works will lose the focus.

Response 1: We have made the introduction shorter and cut out some detailed information about different models and approaches. However, we retained critical information about existing methods and listed issues that are relevant to CME forecasting. There were 104 lines in the part you linked, now there are 49 (lines 49 to 108).

Comment 2: The line 41 -43, you provided some results of your work, but this results give quite strange impression to me.  Why?  You have only provided error bars and standard deviations, but not provided the mean value (average value). This makes difficult to understand straightforwardly what you have done.

Response 2: These results are not results of our work but results from P. Riley (2018) and CCMC Scoreboard research team that describe CME forecasting models (that participated in CME Scoreboard project and operated in near real-time) and summarize modern achievements in the field. We linked this work and results within it to indicate the relevant state of the CME forecasting.

We specified that it the results of P. Riley (2018) in the article to avoid misunderstanding.

We don’t provide the average error, but the average absolute error (MAE), because it indicates the mean value of both positive and negative errors, while the average error indicates only a trend to overestimation or underestimation of the CME arrival time. For example, errors could be + 24h and -24h, producing a mean error of 0h and MAE of 24h. In other case errors could be +8h and -4h and mean error would be +2h and MAE = 6h. Mean error does not produce an accurate understanding of forecasting accuracy in these cases. However, mean error also is an important parameter, so we have added this information in line 42

“.According to the research [2], mean error varies from -7.1 to 0.2 hours, mean absolute error of arrival time prediction – from 13.1 to 17.3 hours, and standard deviation is in range of 15.5 to 23.8 hours.”

Comment 3: I had trouble to understand the term; the “drag-based” model. I read another paper that you have referred in your paper and understand it (by T. Zic et al).  On line 229, there are plus term and minus term.  Plus is pushing force from behind by the fast solar wind and minus means the drag by the collision. However according to your list of CME from the paper that you have published in “Cosmic Research” (2021) in Table 1, the average velocity of CME is around 400 km/s. Is it nearly the same speed of the solar wind?  Therefore it is not so dominant effect on CME that acts the drag force or pushing by the solar wind?

Response 3:

You are right, the average CME velocity is close to the average ambient solar wind speed. However, in each particular case the difference can be enough significant. The solar wind speed distribution usually demonstrates two peaks (one of the last study on this topic: C. Larrodera and C. Cid, 2020, https://doi.org/10.1051/0004-6361/201937307) related to the fast and slow components of the solar wind. We have examined our data and found that the absolute value of the difference between the CME speed and the background solar wind is less than 100 km/s only for 30% of the events. For other events, drag and pushing effects are more pronounced. Velocity distribution for 181 events you can see in figure 1 (attachment). We are planning to publish an article about the interaction between CMEs and background solar wind for various speed differences in the future, so we have decided not to include this information to the present work.

 

Comment 4: I have a question on your formalism on line 199.  The CME speed depends on “constant term + corona hole area”.  Is it true?  I thought high speed solar wind is frequently observed from the Solar Polar Regions.  I should check it to solar wind specialist. But don’t you put the difference of high speed solar wind and low speed solar wind into your analysis (also the latitude parameter)?

Response 4.The formula that we use is described in details in the original research by Yu. Shugay, 2011 (https://doi.org/10.1134/S0038094611060086). The core idea is that quasi-stationary (reccurent) solar wind streams are produced by two components: slow wind from coronal streamers and fast wind from coronal holes. The second component can be predicted by empirical relation between solar wind speed and coronal hole parameters (see Robbins, Henney, and Harvey, 2006; Veselovsky et al., 2006; Vrsnak, Temmer, and Veronig, 2007; Luo et al., 2008; Obridko et al., 2009). Slow solar wind is difficult to predict accurately as its particular source is hard to determine. In our model we take into account only a fast wind from the coronal holes, and when no coronal hole is observed we use 300 km/s (constant term).

We agree that coronal holes are frequently observed in the Solar Polar Regions, especially during the solar minimum. However, during solar maximum and declining phase, coronal holes occur at lower latitudes and even at solar equator. They became the important sources of magnetic disturbances during these periods. We add such example at the new section, where we describe forecasting process for one particular event. You might also be interested in some equatorial coronal hole research (N. Karna et al 2022 https://doi.org/10.3847/1538-4357/ac3c46, G. Verbanak, 2010, https://doi.org/10.1051/0004-6361/201014617)

Comment 5: Line 244. You have only mentioned the drag effect, but is there no effect from the pushing effect (acceleration) by the solar wind?

Response 5: You are correct about the possibility of both drag and pushing effects, and the both are accounted for in our research. In the terms used in this paper, the rate of the drag effect is expressed by the drag parameter γ, while the modality of the effect (acceleration or deceleration) is determined by the sign of the difference between ICME speed and ambient solar wind speed. The pushing effect is thus described as drag of the solar wind on the ICME. The drag parameter term only expresses the rate of change of speed and is always positive. To improve clarity, we use the phrase “drag parameter value” instead it (Line 202).

Comment 6: Section 2.4 “event selection”.  This part is easier to read.  So for paper writing, the main focus should be given on these contents.

Response 6: Thank you. We agree that this part is important and we have added figures with an example here to make it clearer (Figure 1). We also got rid of the duality of filtering stages: there were four Steps and five Filters in parallel. Now it’s only four Steps (Table 1).

Comment 7: Line 269.  Why 240-300 degrees corresponds to the equatorial CME?  Is it .120-240 degrees?

Response 7: We have added an illustration (Figure 1) to explain the angular axes we use for coronagraph images. Equatorial CMEs refer to CMEs that are more likely to propagate near the ecliptic plane.

Comment 8: Line 272. CME-dimming should be “CME dimming event”.  There are plenty of this word (dimming) in this paper.  Please check them by yourself.  It is quite hard what it relates with the real coronagraph image.

Response 8: We replaced “CME-dimming correspondence” with “correspondence between CME and coronal dimming” (Lines 232, 245, 619, 624). Coronal dimmings are separate phenomena that can be observed in SDO/AIA difference images. We changed the term “dimming” to “coronal dimming”. We also added examples to illustrate the coronal dimming and CME relationship (figure 1, figure 7)

Comment 9: Line 292.  What does off-limb events point out?? Please include more detail explanation on this, for example, in the table caption of Table 1.

Response 9. Here we mean events with longitude close to 90 or -90 degrees. We observe dimmings for such events above the solar disk and we can easily identify them by the following criterion: R_dist >=1. R_dist indicates the distance from the solar disk center to the geometrical center of the dimming on SDO images, expressed in Solar radii. So R_dist =1 refers to the edge of the solar disk.

We have expanded the Table 1 title (Line 280): “”Off-limb” event means that CME corresponds to dimming with R_dist >= 1 (i.e. longitude is around +90 or -90 degrees)”

Comment 10:Line 302.  What do you mean “narrow events filter”?  Slightly detail explanation should be added.

Response 10: We have corrected “narrow events” to “events with small angular width”. We have added in the Table 1 title (Line 279): “Small angular width is less than 30 degrees for equatorial CMEs and less than 60 degrees for polar ones.”

Comment 11: Line 347-349. There need three pictures for each case.

Response 11: We used classification of SW type sequences connected to ICMEs that has been developed by Space Research institute. This catalog of the large-scale solar wind phenomenon is the product of Yuri Yermolaev and SRI team. We used their catalog only to complete our ICME list in addition to two other ICME data catalogues (Richardson and Cane ICME list and CCMC CME Scoreboard data). Solar wind parameter profiles are not needed for our purposes. However, we added the links to SRI catalogue (e.g. https://doi.org/10.48550/arXiv.1610.03757 ), where such figures can be found.

Comment  12: Line 351-362.  It is difficult to understand what you want to say here.

Response 12: We have rewritten this part to make process of making ICME list more clear (Lines 328-347)

We have combined three lists into a unified list and merged events that match between initial lists to avoid duplicates. When compiling the unified list, events are merged if their time parameters match within certain tolerances. Merging is performed in the following order:

1. Events from Lists 1 (R&C) and 2 (CCMC) are merged if their shock arrival time matches with a tolerance of ±6 hours.
2. Events from List 3 (SRI RAS) are merged with events from List 1 and 2 by shock arrival time with the same ±6 hour tolerance.
3. Events from List 3 that haven’t been already merged with List 1 and 2 are merged by start time with a tolerance of ±24 hours.
4. Finally, remaining List 3 events are merged with List 2 events that originate from the CCMC CME scoreboard if the difference between the start time of the List 3 event and the shock time of the List 2 (Scoreboard) event is less than ±24 hours, since the CCMC CME Scoreboard does not provide CME start times.

We calculated solar wind average and maximum speed and minimum Dst index value for each ICME from final list, using hourly data from the OMNI database. The average speed for each ICME was calculated for the period of the ICME ejecta/MC observation time indicated in the catalogs. In cases when only ICME shock wave arrival time were known, this time was used as ICME start time and the duration of ICME were established as 20 h. Solar wind maximum speed and minimum Dst index value were calculated similarly.

Comment  13: Line 262.  I can access the first page of your web site, but I cannot enter in each column in your web site.

Response 13:

We are sorry for this inconvenience. Possibly, some technical works were performed on Web-site.  We checked the page https://swx.sinp.msu.ru/tools/icme_list.php and found that it was available on 28.06. It contains a simple table with ICME time parameters, solar wind speed parameters and minimum Dst index values for each row. The table is not interactive. The screenshot is presented in figure 2 (attachment).

  

Comment 14:  I propose you to insert new sub session like “2.5 list making process”. Because your explanation try to explain different subject from line 255 to 330. It would make easier for readers to understand what you would like to say here.

Response 14: We agree. We have added the subsection (line 296) “2.5 ICME list for model validation”.

Comment 15:  Line 373-374. The weak CME will make the geomagnetic events?  From a point of view of space weather? Line 375 to 379, it is interesting!

Response 15: Any CME, any solar wind variation has geomagnetic effect. Of course, weak CMEs aren’t of great interest from a space weather perspective, since they don’t pose a serious threat to the earth's infrastructure. However, they are highly relevant to solar wind modeling in general, so we included such events in our validation set. There are various reasons why an ICME can be “weak” at Earth. For example, it can be a powerful CME that impacts Earth from the side (glancing blow), resulting in insignificant ICME signatures and impact on Earth magnetosphere. Every disturbance in the solar wind will cause a magnetospheric response, so in our opinion it is important to consider such events.

To avoid possible misunderstandings, we have updated the text (Line 361): “…events that don’t intersect between lists are generally weaker and shorter events that don’t lead to significant geomagnetic disturbances”

Comment 15*: On Table 4, I strongly recommend to present the results on the figures. Like Figure 5 of your paper “Cosmic Research” in 2021.  In the graph of Cosmic Research, the center of the horizontal axis is set at 0 hours.  I suggest you to replace 0 to actual average hour and one more graph actual average velocity.   Please make two figures for the arrival time (TOA distribution) and average velocity. Then the 2day, one day parameters would be much more easily understood.  Table 5, also the same.  Figure is better.

Response 15*: We have added such figures to the article. We have produced TOA and SOA distributions for the set of hit events (see Figure 5). However, these figures do not contain all the information from Tables 4 and 5, so we didn’t remove them. We decided to keep results about hit, miss and false alarm in the tables as well. We added some text to describe this figure (Lines 449-452, 508-510)

 

Comment 16.  Line 394. TAO should be TOA. Simple typing mistake. Typo.

Response 16: Fixed. (Line 381)

Comment 17.  Line 460-461.  Is it better to add new sub session like “3.2 comparison with other works….”

Response 17: We have added a new subsection. (Line 455) “3.2 Comparison with WSA-ENLIL + Cone model”

Comment 18.  Line 464-479.  Please specify your work and the other works more clearly. Line 484-485, I can understand that this is your work.  Like that.

We have rewritten this part to make it shorter. We have also specified which information is about our work and which is about other models. (Lines 460, 464-465, 466, 469,471,474,478)

Comment 19.  Line 490-491.  It may be a conclusion.

Response 19: We have expanded the conclusion. (Lines 604-606)

Comment 20.  Line 515. -58.1 km.  This is in Major disturbances, a high speed CME is involved.  One of the example may be 2004.11.6-7 event.  The CME run with high speed exactly 1,000km/sec in 1AU.

Response 20: Agreed

Comment 21.  Line 517-520.  I agree this descriptions.!

Comment 22.  Line 524-547.  From the space weather forecast point of view, these contents may be not essential.

Response 22: We consider this part relevant to understanding how CME modeling differs at different phases of the solar cycle and for events of various geoefficiency. So, we decided to keep this part.

Comment 23.  Line 549. Results of the Moscow State University Space Monitoring Data Center.  It would be better to put full spelling here. Also for CACTus à Computer Aided CME tracking software.

Response 23: We agree and have corrected this in the Line 589. We have also added full name of CACTus in the Line 114 (where first mention).

Comment 24.  Line 564-586. Dimming à Dimming “events”. Lines 564, 575, 577, 580, 584, 586, 591.  The same modifications (addition) are necessary.

Response 24: We have changed “dimming” to “coronal dimming” – it is the more official term of the phenomenon. (lines 106,115, 144,146,146,148, 233-275, 524, 551-568, 605, 617-635)

Comment 25.  Line 590.  What is the 2D DBM simulation?  Two dimensional simulation?

Response 25: Yes, we meant two dimensional simulation and we have added an explanation in Line 634.

Comment 26 .  Line 591-592.  I agree this interpretation.

Comment 27.  Line 602-606.  I agree with this conclusion.

Comments on the Quality of English Language:

This paper is very difficult to read. It is not a problem with the English language. But it arises from the stream of English logic. Furthermore, it is necessary to make the Abbreviations corner, since you use so many abbreviations in the paper. Therefore for readers, it makes hard to follow your logic (avoid lost of logic).

Response: We reviewed article and get rid of long and complicated sentences. We rewrite some parts to make our explanations clear. We add Abbreviations corner (Lines 677-717).

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The paper presents an algorithm to forecast the velocity and arrival time of  ICME at Earth using a one-dimensional drag-based model. The methods are described in detail as well as the discussion of the databases from where input parameters were derived. The results are presented clearly and the discussion of the limitation of the model in terms of prediction power is also illustrated. The authors conclude that the presented model provides performances similar with respect to other existing approaches but could be improved for example with a two-dimensional model.

In my opinion the paper could be accepted in the current form and does not need any major revision.

Below a list of typo:

Page 1 - line 34: "working is this field" -> "working in this field"

Figure 1 - Would be helpful to have one line and one dotted line, in case someone would read the paper on a non-color device

Page 8 - line 320: "Misses" -> "miss"

Page 10 - line 394: "(TAO)" -> "(TOA)"

Figure 3: Same as figure 1, would be helpuful to have the three line in three different style.

Author Response

The authors express their gratitude to the reviewer for the notes and recommendations. We were glad to follow your ideas to improve our work.

Response: We have fixed all typos you mentioned and have changed line styles on figures 1 and 3 (numbered figures 2 and 4 in the new version). Thank you very much for your attention to our research.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

I will point out the parts that are better to be improved.

Line 16    single out à select (simply)

Section 1 (Introduction) better than former case to read.

Line 46,49; Please define “low” corona more clearly.

           Also a “mid term” forecast.  What do you mean “mid”?

Line 54 toderive à to derive, What is ENLIL? 

There is no explanation at Abbreviation corner.

Line 78-79; Can they do the real time prediction by the ELEvoHI model?

           In this page, your main critical points are that all they are

           Unable the on-line prediction. By your method, is it possible?

           If so you should mention it in Introduction.

Line 107, Taking account of your discussions, it would be better to stress

           Here, the corona dimming effect.  Otherwise, logically

the description in line 103 to 108 does not actively work.

Line 105-116, There is no explanation on Solar Demon database, even

             In the abbreviation corner.

Section 2  Page 4 and 5 are easier to read out.

Line 195, “The drag based model (DBM)” is better.

Line 229-231, New introduction of Figure 1, makes easier to understand

           What you have done. Good!

Line 236, `Please define “Low” corona by the unit of the solar radii.

Line 255, Please add a short explanation on off-limb event. 

         What is off-limb event?

Line 258, What is pa>180?  What is “pa”? 

Page 8; general comment.  It is not so easy to understand what do you

want to say here. Please write clearly and simply.  Especially,

Line 324,325m326, You need explanation what kind of selection

Did you do.  What is the difference of these three ?  It would be

Better prepare some drawings here.

Line 345-346.  This explanation provides some misunderstanding.

      If we cannot measure the ICME start time and we know only the arrival time, the, you can use the arrival time as ICME start time. This statement is strange!  Did you set the flight time always 20 hours??

     I can read as above.

Section 3 Results

Line 398-400.  The explanation is inaccurate.  You must add a few

              Lines for the explanation here.

Line 474, The authors consider a simulation a miss.

         I think this sentence includes some typing mistake.

On Table 7 of page 16, It would be better to add the reason below,

          Whys the initial CME speed of 1135km/sec was reduced as

          637(SOA) km/sec?  Was it due to the interaction between

          Precedent solar wind (drag effect)? 

          If the CME departed near solar limb as the speed of 1135km/sec,

          It is expected to arrive at the Earth near the time of predicted by

          WSA-ENLIL+Cone (NOAA/SWPC) prediction.  Why did it arrive

          At 19:59 UT of January 9^th??

Line 611, 48 hours error ( 2days), may be too large for the actual use as

          The space weather forecast?  How do you consider about it?

          From the practical (use) point of view?

Line 627-631, Then why don’t you include this method (use of corona diming)

          in the abstract?

 

Author Response

Response

The authors are very grateful to the reviewer for his contribution to the work on the article. Thank you very much for your valuable comments and suggestions and for the time and attention you devoted to our work. It was interesting and useful for us to follow your recommendations.

Here is our responses to your comments.

Comment 1: Line 16    single out à select (simply)

Response 1: We replace “single out” with “select” to simplify the sentence.(Line 16)

”…a new algorithm was established to select events that can reach Earth more likely.”

Comment 2: Line 46,49; Please define “low” corona more clearly.

Response 2: Here we meant the distances up to 20 solar radii. We specified this at line 47

“…such as CME evolution in the solar corona up to 20 solar radii…”

Comment 3: Also a “mid term” forecast.  What do you mean “mid”?

Response 3: Here we meant 2-5 days in advance. We specified this in the article (Line 50)

“…a mid-term forecast (2-5 days in advance).”

Comment 4: Line 54 toderive à to derive

Response 4: Fixed. Thank you! (Line 55)

Comment 5: What is ENLIL? There is no explanation at Abbreviation corner.

Response 5: Enlil is not an abbreviation but the name. Enlil is an ancient Mesopotamian god associated with wind, air, earth, and storms.

Comment 6: Line 78-79; Can they do the real time prediction by the ELEvoHI model? In this page, your main critical points are that all they are unable the on-line prediction. By your method, is it possible? If so you should mention it in Introduction.

Response 6: ELEvoHI model can do real-time predictions technically and source code is stored in the GitHub. However, there is no online application with ELEvoHI predictions and open storage of all real-time predictions. Their approach needs manual CME fitting and real-time application is under development now as we write in Line 79-90 ref [22]. In paper (Bauer et al, 2021, Space Weather, Volume 19, Issue 12, https://doi.org/10.1029/2021SW002873) they noticed:

“ELEvoHI is commonly used with STEREO-HI science data, which have a higher spatial and temporal resolution but are not available in real-time, to make predictions. The model has the capability to deliver near-real time predictions for arrival time and speed if beacon data, which are downlinked in near-real time, are available for the desired time frame.”

It is possible to do real-time forecast by our method, but we have not finalize our on-line application yet too. However, all parts of our method can operate automatically and in the real-time mode and the full process is described in the present work. We focused on this in the conclusion lines 604-606:

“The system is ready to be launched to make predictions in near-real time mode and all results were obtained using only data available in near real-time.”

Comment 7: Line 107, Taking account of your discussions, it would be better to stress Here, the corona dimming effect.  Otherwise, logically the description in line 103 to 108 does not actively work.

Response 7: We added more focus on dimmings here (Line 109-112):  

We applied a similar approach in the present work, using coronal dimmings coordinates estimated from SDO images for selecting Earth directed events. For this purpose, we used Solar Demon database [32] that was developed to detect coronal dimmings and list their parameters.

Comment 8: Line 105-116, There is no explanation on Solar Demon database, even In the abbreviation corner.

Response 8: We add mention of the Solar demon data base in line 110, and we described it in details in section “2. Materials and Methods-> 2.1 Data” in Lines 151-155. This name is not included in the abbreviation corner because it is not an abbreviation, just a name.

In addition to the CACTus database, we use the Solar Demon dimming detections database [39]. A coronal dimming is a decrease in the intensity of soft X-ray and EUV radiation of a region of the Sun [40–42]. Solar Demon software processes SDO/AIA 21.1 nm images in real-time, detects coronal dimmings and automatically obtain their properties. The wavelength of 21.1 nm corresponds to Fe XIV emission at 2 million Kelvin and shows active regions of solar corona. These conditions are associated with height of 1.1-1.5 solar radii (lower corona).The Solar Demon database provides a number of properties of each event such as coronal dimming observation start and end time, intensity, coordinates and area dependence on time with a 2-minute resolution. Since one of the causes of coronal dimmings are fluctuations of plasma density due to CME expansion and escape from the solar corona, it is possible to use coronal dimming data to estimate CME source location and propagation direction or to detect stealth CMEs [43].

Comment 9: Line 195, “The drag based model (DBM)” is better.

Response 9: Thank you, we fixed this. (line 200)

Comment 10: Line 236, `Please define “Low” corona by the unit of the solar radii.

Response 10: We specified height here (line 244)

As mentioned, the appearance of a coronal dimming is a consequence of CME motion in the low corona at the height of approximately 1.5 solar radii, but we observe dimmings earlier because the CME needs some time to reach the field of view of the LASCO C2 coronagraph, while the dimming is observed directly at the CME launch area.

Comment 11: Line 255, Please add a short explanation on off-limb event. What is off-limb event?

Response 11: We added here (Line 264)

“Off-limb events” are events that occur at a longitude of around +90 or -90 degrees and are observed from the L1 point above the solar disk.

Comment 12: Line 258, What is pa>180?  What is “pa”? 

Response 12: We corrected here pa to positional angle. (line 268)

Comment 13: Page 8; general comment.  It is not so easy to understand what do you want to say here. Please write clearly and simply.  Especially, Line 324,325m326, You need explanation what kind of selection Did you do.  What is the difference of these three ?  It would be Better prepare some drawings here.

Response 13: We added detailed description of an ICME structure in Lines 312-315

The general structure of an ICME comprises an interplanetary shockwave, characterized by shockwave arrival time (T_shock), followed by a turbulent sheath region and then by the ICME body, which is characterized by body detection start and end times (T_start and T_end). There is also a further classification of ICME body types as either “ejecta” or “magnetic cloud” (MC)[50–53].

We also introduced there T_shock, T_start and T_end parameters, that are used to produced unified ICME list from Lists 1,2,3 and OMNI data.

To produce ICME List 3 we used SRI RAS Catalog of Large-Scale Solar Wind Phenomena. SRI RAS list contain solar wind streams connected to slow and fast solar wind, CMEs and corotating interaction regions. From this list we selected only types connected with the ICME structure.

So the typical ICME structure is described by the consequence of shockwave, sheath region and ICME body (ejecta or magnetic cloud, or both) (see figure 1 in the attachment from the article by Richardson et al 2011 DOI: 10.1007/s11207-011-9774-x). However, it can be difficult to indicate all three parts in the in-situ data. The sheath region or both the sheath region and the shockwave are sometimes absent, either because they were not detected or because they were very close to the ICME body (cannot be detected in 1 hour averaged data which are commonly used).

That’s why we select following tree variants of sequences from SRI RAS list: Ejecta/MC; Shockwave + ejecta/MC; Shockwave + sheath region + ejecta/MC.

If no ejecta/MC detected, this means that the main part of ICME doesn’t hit Earth. Also the consequence of shockwave + sheath region with no ejecta/MC may indicate Corotating Interaction region propagation. So we don’t include shockwave + sheath region or just shockwaves in List 3. This ICME types selection are connected only to SRI RAS Catalog of Large-Scale Solar Wind Phenomena. In the Richardson&Cane ICME list and CCMC CME Scoreboard data only ICME data are presented, so we don’t need to make addition selection.

We changed some details in this subsection to clarify this moments (Lines 325-341)

Comment 14: Line 345-346.  This explanation provides some misunderstanding.  If we cannot measure the ICME start time and we know only the arrival time, the, you can use the arrival time as ICME start time. This statement is strange!  Did you set the flight time always 20 hours?? I can read as above.

Response 14: We rewrite this part to clarify this moment (Lines 360-364)

For most events, ICME observation time was assumed from T_start to T_end. For some events only CME shockwave arrival time (T_shock) is known, and for such events we assumed ICME observation time of 20 hours starting from T_shock. The duration of 20h were assumed since this is the average ICME duration for ICMEs with known T_start and T_end.

Comment 15: Line 398-400.  The explanation is inaccurate.  You must add a few Lines for the explanation here.

Response 15: We name time parameters here (lines 415-416)

“…and  is the ICME start time (T_start) from the merged ICME list if it is known and the ICME shock arrival time (T_shock) from the merged ICME list for ICMEs with only shock time indication.”  

Comment 16: Line 474, The authors consider a simulation a miss. I think this sentence includes some typing mistake.

Response 16: We corrected: The authors classify a simulation as a miss. (Line 490)

Comment 17: On Table 7 of page 16, It would be better to add the reason below, Whys the initial CME speed of 1135km/sec was reduced as 637(SOA) km/sec?  Was it due to the interaction between Precedent solar wind (drag effect)? If the CME departed near solar limb as the speed of 1135km/sec, It is expected to arrive at the Earth near the time of predicted by WSA-ENLIL+Cone (NOAA/SWPC) prediction.  Why did it arrive At 19:59 UT of January 9^th??

Response 17: You are right, the CME is decelerated according to our simulation due to the drag effect. Enlil used a different initial speed estimation method and obtained higher initial speed (more than 2000 km/s), that’s why they obtained earlier TOA.

Comment 18: Line 611, 48 hours error ( 2days), may be too large for the actual use as The space weather forecast?  How do you consider about it? From the practical (use) point of view?

Response 18: Thanks for noticing this, we corrected 48->24h (Line 631). You right that 48 and even 24 hours accuracy is not excellent for space weather purposes. However, all existing models could give such errors in some cases. The average error and average absolute error are usually smaller. We showed that in our work more than 40% of hit events have errors less than 24h (fig 5a)).

 

Comment 19: Line 627-631, Then why don’t you include this method (use of corona diming) in the abstract?

Response 19: Thank you for such a good idea. We agree that such key information should be added in the abstract. (Line 17)

Coronal dimming data were used to obtain coordinates of the CME source location. 

Author Response File: Author Response.docx