the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 17 Sep 2025
Global geomagnetic response to repetitive geospace storm of March 21–25, 2024
Abstract. The geomagnetic storm of March 21–26, 2024, was comprised of five storms, i.e., it was a multi-step storm, with the main storm occurring during March 24–25, 2024. A multi-step nature of this storm is unique to this event, and this storm is due to isolated sheaths that appeared in the solar wind. The power of the geospace storms caused by increases in the solar wind dynamic pressure was close to 29 TW, 33 TW, 50 TW, 174 TW, and 192 TW, and their energy did not exceed 0.73 EJ, 0.59 EJ, 0.36 EJ, 2.5 EJ, and 2.8 EJ. The power of the magnetospheric storms being due to increases in the interplanetary magnetic pressure were 13 GJ/s, 13 GJ/s, 130 GJ/s, 1000 GJ/s, and 190 GJ/s, and their energy attained 90 TJ, 90 TJ, 1360 TJ, 22,000 TJ, and 2000 TJ. The energetics of the magnetic and kinetic pressures has been shown to be close to each other. The maximum power of the geomagnetic storms was close to 93 GW, 97 GW, 208 GW, 283 GW, and 89 GW, and their energy were smaller than 3 PJ, 1.4 PJ, 3 PJ, 5.1 PJ, and 4.5 PJ. The storms of March 21–22, 2024; March 23, 2024; March 23–24, 2024; March 24–25, 2024; and March 25–26, 2024, pertain to the storm classes G1 (minor), G1 (minor), G2 (moderate), G4 (severe), and G0 (very minor). In both the eastern and western hemispheres, the peak-to-peak amplitude of variations in a geomagnetic field strength exhibited a tendency to increase with increasing magnetic latitude. At high latitude stations, the peak-to-peak amplitude attained a maximum value of ~1000–2000 nT, whereas at mid- and low latitude stations they were observed to be within ~100–300 nT. The observed possible deviations from the tendency indicated above may be due to the different physical processes acting to cause variations in the geomagnetic field at high, middle, and low latitudes. The peak-to-peak amplitude of variations in a geomagnetic field strength was observed to be the greatest during sunlit hours. The peak-to-peak amplitude of variations in a geomagnetic field strength during the storms was a factor of up to 23–28, 19–23, and 15–19 greater than that during quiet time reference period, in the northward X-, eastward Y-, and vertical Z-component of the geomagnetic field, respectively. The storm of March 24–25, 2024, termed the main storm, was the most intense of all five storms of March 21–26, 2024. The main storm of March 24–25, 2024, is comparable to the storm of April of 23–24, 2023, with respect to all its parameters. At the same time, it is less intense than the storm of May 10–11, 2024, the strongest storm of solar cycle 25, and even less intense than the Carrington event.
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Status: open (until 29 Oct 2025)
- CC1: 'Comment on egusphere-2025-4375', Yiyang Luo, 18 Sep 2025 reply
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CC2: 'Comment on egusphere-2025-4375', Yiyang Luo, 18 Sep 2025
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This manuscript presents a detailed and timely analysis of the multi-step geomagnetic storm of March 21–25, 2024. The study is well-structured, data-rich, and provides a comprehensive examination of the event's characteristics, including its multi-step nature, global magnetic field response across both hemispheres, and a thorough energetics analysis. The comparison with other significant storms of solar cycle 25 and historical events is a valuable contribution. The work is suitable for publication pending minor revisions to improve clarity, context, and the discussion of certain methodological choices.
Major Comments:
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Clarity on Storm Identification and Drivers: The manuscript effectively identifies five distinct storm periods. However, the physical driver for each step could be more explicitly stated. The discussion in Section 6.1 suggests they are all caused by "sheaths," but the text also notes significant differences (e.g., the March 24 storm was "due to high-speed solar wind plasma streams" and the March 25 storm occurred under northward IMF). Please clarify the proposed solar wind structure (e.g., CME sheath, CME ejecta, CIR) responsible for each of the five enhancements. A summary table linking each storm step to its proposed solar driver (if identifiable from solar observations) would significantly strengthen the paper.
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Contextualization of the "Repeatable" Nature: The abstract and introduction highlight the "unique" multi-step/repeatable nature of this event. While five clear pressure pulses in quick succession are notable, multi-step storms are not unprecedented (as correctly referenced with the April 2023 event). Please moderate the language (e.g., "relatively unique" or "a notable example of a multi-step storm") and briefly discuss in the introduction how the repetition rate and intensity of these steps compare to other documented multi-step storms, to better frame its significance.
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Methodology for Energetics Calculations:
- The energetics calculations are a core strength. However, the choice of constants and assumptions should be briefly justified. For example:
- The use of a fixed magnetosphere cross-sectional radius of 10 R_E for S_m0 is standard but simplified. A sentence acknowledging this common assumption would be sufficient.
- For the geomagnetic storm energy (E_ms, Eq. 6), please specify the values used for constants b and c in the D_st* correction, as different values exist in the literature. A citation for the chosen values (e.g., Gonzalez et al., 1994, as referenced) is essential.
Minor Comments:
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Abstract: The abstract is very dense. Consider slightly simplifying the list of numerical values (e.g., "...ranging from 29 TW to 192 TW" instead of listing all five) to improve readability for a broad audience, while keeping the key conclusions.
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Section 3 (Space Weather State): The description of the solar wind parameters is very detailed but somewhat narrative. Consider integrating a panel of Figure 2 directly into the text of Section 3 (e.g., "As shown in Fig. 2a, n_sw exhibited five enhancements...") to make the description more concise and directly linked to the data.
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Tables 3 & 4: The peak-to-peak amplitude values are central to the results. Please consider adding a final row to these tables showing the average or median value for each component across all stations for each storm day. This would provide a quick, quantitative overview of the storm's global intensity evolution.
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Section 6.5 (Latitudinal Dependence): The explanation for deviations from the simple latitudinal trend is excellent. To make it even stronger, you could briefly mention the local time effect, as the stations are not all on the same meridian, so latitude and local time/MLT effects are conflated.
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Typo/Clarity: Page 13, Table 5: The header "β of the plasma" might be clearer as "Plasma β" or "Plasma beta (β)".
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References: The reference list is extensive and appropriate. Please ensure all in-text citations have a corresponding entry in the reference list (e.g., Chernogor, 2025a is cited in Section 6.1 but the full reference appears to be missing from the list provided in the manuscript text).
Conclusion:
This is a robust and valuable study that provides a comprehensive analysis of a significant space weather event. The authors have done an excellent job in processing a large global dataset and presenting a multi-faceted analysis. The requested revisions are minor and aimed primarily at enhancing clarity and context. I am confident the manuscript will be a strong contribution to the literature after these points are addressed.
Citation: https://doi.org/10.5194/egusphere-2025-4375-CC2 -
AC1: 'Reply on CC2', Leonid Chernogor, 30 Sep 2025
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The author is sincerely grateful to Yiyang Luo for his helpful comments.
Multi-step storms are indeed associated with “sheaths”. Furthermore, in some cases, such as on March 24, the influence of high-speed solar wind plasma streams was superimposed. Therefore, we clarify that “this storm was intensified by high-speed solar wind streams”. As we can see, there are no contradictions. As for the storm of March 25, its mechanism is different. It is most likely related to the aftereffects of the March 24 storm. A more detailed description of this storm would require extensive physical simulation, which is beyond the scope of this paper.
In the author's opinion, the inclusion of a summary table would largely duplicate information already presented in the main text. This will only increase the volume of the manuscript.
Regarding “uniqueness”. Indeed, multi-step storms are observed in approximately 67% of cases. However, this applies primarily to two-step storms and much less to three-step storms. The event described in this study is a five-step storm, which is exceptionally rare and, therefore, can be considered truly unique.
Methodology for energetics calculations. This paper uses a magnetospheric cross-sectional radius of 10RE. This is the same value used by all authors. During storms, the longitudinal extent of the magnetosphere contracts. It is described by the Chapman-Ferraro radius. Therefore, the use of 10RE values is fully justified.
The values of the constants b and c are well known. The citation to Gonzalez et al. (1994) has been added to justify the chosen values.
About minor comments.
1. The author believes it is appropriate to include all numerical values in the abstract. They help compare the intensities of all five storms, which indicates the uniqueness of the March 2024 event.
2. The following has been added to the text: As can be seen from Fig. 2, significant spikes in particle number densities...
3. Regarding Tables 3 and 4. Providing average values of component levels for all stations is simply not practical. The effects depend significantly on latitude and longitude (local time), which is one of the main results of the study. Presenting a simple average is as uninformative as citing the average body temperature of all patients in a hospital.
4. This is absolutely correct. Of course, the effects depend on local time. This is stated in the text: “disturbances… are distributed in longitude and latitude highly unevenly...”. The non-uniformity in longitude is determined by local time. To clarify this further, the author has added the following sentence after the words “longitudinal dependences of the magnetic effect”: The dependence on longitude is directly related to local time.
5. The typo has been corrected.
6. The references have been verified and corrected.Citation: https://doi.org/10.5194/egusphere-2025-4375-AC1 -
RC2: 'Reply on AC1', Yiyang Luo, 04 Oct 2025
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With all comments now addressed, the paper is in excellent condition.
Citation: https://doi.org/10.5194/egusphere-2025-4375-RC2
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RC2: 'Reply on AC1', Yiyang Luo, 04 Oct 2025
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RC1: 'Comment on egusphere-2025-4375', Anonymous Referee #1, 30 Sep 2025
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The article addresses an important topic of characterizing multi-step geomagnetic storms, driven by a combination of CME/ejecta and sheath regions. The article uses the recent superstorm of March 2024 as an example. The article could potentially be publishable after substantial revisions. Many statements in the article appear to be not clearly justified. I also have doubts about the validity of some approximations/methods, e.g., the Eq. 1. Many sections of the article contain very long and unnecessary descriptions of various max/min values, that could be seen from the graphs. Many other sections can be shortened. The conclusions need to be substantiated. Also, I suggest to add some references to previous studies of multi-step storms. The specific comments are listed below.
Line 7: “Multi-step nature” is not unique to this storm, need to clarify.
Line 33: Not sure what “litoshpheric storm” means in connection to geomagnetic storms. Please explain.
Line 46-80: This section, which comprises the most of Introduction, describes all different storms of cycle 24, while the article is dedicated to one specific storm of March 21-25, 2024. This is not a review the solar cycle, and there is no need to describe all other storms. In my view, the entire section 46-80 can be removed. Instead the author should focus on specific features of the storm they consider in this article.Line 77: The author should clarify further what is meant by “repeatability”, with references to previous studies.
Line 81: It is not clear what the author means by “raw data”. Later in the article they describe high-level processed data products, e.g., from OMNI. I have not seen any raw data. Probably the author means “available data”.
Line 85: What is “super unique Carrington-like event”? Please clarify.
Line 91: “It is well known” is a meaningless statement, should be removed.
Line 98: Just a note that March 27 day is in the storm recovery phase, it’s not really a quiet time.
Line 114: nsw from OMNI is probably the solar wind number density, not the proton density, though the difference is marginal.
Figure 2: The coordinates of IMF data should be specified, see also the following comment.
Line 147: While the Akasofu parameter is well known, it would be useful to give the formula, and the reference to the original Akasofu’s work is definitely needed, e.g., Akasofu, 1979. The author should also note that the Akasofu parameter was proposed originally without clearly specifying the IMF coordinates, but it is customary to use the GSM coordinates, see Koskinen & Tanskanen, 2002, https://doi.org/10.1029/2002JA009283
Line 167: The sentence “storm commences in the second half of March 21, 2024, and continues until ~12:00 UT on March 21, 2024” is unclear. Looking at the Dst index in Fig. 2, the storm’s main phase continues till about 21 UT on March 21, when the Dst minimum is reached.
Line 165-260: In this section, the author simply summarize the min/max values of magnetic field variations, which are anyway presented graphically. This very long summary of values is absolutely unnecessary and could be removed or reduced to a short summary.
Line 265-270: I am puzzled by the method to quantify the energy supplied to the geospace medium during the storm. Should not this energy be dependent also on the IMF orientation, in addition to the dynamic pressure? This follows, for example, from the Akasofu parameter which the author calculated earlier. I would expect that the magnetosphere cross-section/shape will change during a major geomagnetic storm, and would also depend on the IMF direction, e.g., for the southward IMF the reconnection takes place near the subsolar point, but for the northward IMF at the flanks. Every solar wind – magnetosphere coupling function that I am aware of includes some info about the IMF orientation, at lease the sign of IMF Bz. See the comprehensive review of coupling functions by Newell et al., 2007, https://doi.org/10.1029/2006JA012015. The validity/limitations of this method should be discussed.
Line 317: This is a misleading definition of sheath region. The main characteristics of sheath is the high plasma beta parameter (while ejecta has low plasma beta) and high level of turbulence / magnetic fluctuations, because the sheath region is highly compressed and disturbed. Please clarify the definition.
Line 319: To my knowledge, the first study that analyzed in details the impact of sheath vs CME/ejecta on the Earth’s magnetosphere is Pokhotelov et al., 2016, https://doi.org/10.1002/2016JA023130. They used the multi-step storm of 8-9 October 2012 and data from multiple satellite missions. This study should be referenced and briefly discussed.
Line 335-420: Again, this section contains a lot of unnecessary verbal descriptions of what is shown already in the plots. It could be shortened substantially.
Line 430: The statement “similar to the Carrington event” is unjustified, since we do not know many characteristics of the Carrington event, e.g., the Dst magnitude is unknown. I think a reference is needed to one of the numerous articles dedicated to the Carrington event.
Section 7: The conclusions are somewhat weak. Some discussion here is needed about the driving of magnetosphere by sheath regions vs ejecta/CME regions, see Pokhotelov et al., 2016 and Kilpua et al., 2017 for discussion.
Citation: https://doi.org/10.5194/egusphere-2025-4375-RC1 -
CC3: 'Comment on egusphere-2025-4375', Leonid Emelyanov, 01 Oct 2025
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This manuscript presents a detailed description and analysis of a multi-step geomagnetic storm of March 21–26, 2024, with the main storm occurring during March 24–25, 2024. The study is based on an extensive dataset obtained from high-, mid-, and low-latitude stations in both the eastern and western hemispheres. A large amount of experimental data is presented and thoroughly analyzed, including numerous numerical values characterizing each of the five storms of different intensities. Physical interpretation of the results is conducted at a high scientific level. The sources and physical mechanisms of recurring geomagnetic storms are thoroughly considered. Another advantage of the paper is that the main storm of March 24–25, 2024, was compared with other intense storms by a significant number of storm parameters and characteristics.
The introduction accurately reflects the current state of research in the field. The methodology is appropriately described and correctly applied. The study is relevant, contains elements of novelty, and represents an original scientific contribution. The conclusions are well supported by the results. The manuscript is clearly written, logically structured, and accompanied by an adequate number of high-quality figures.
The paper is of interest to specialists investigating the effects of space weather on near-Earth space and, in my opinion, merits publication.
Nevertheless, clarification is required regarding the discrepancy in storm duration: the manuscript states that the geospace storm persisted from March 21 to 26, 2024, whereas the geomagnetic storm is indicated as lasting from March 21 to 25, 2024.
Citation: https://doi.org/10.5194/egusphere-2025-4375-CC3
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This manuscript presents a thorough and valuable analysis of the multi-step geomagnetic storm in March 2024, offering a comprehensive examination of its global magnetic response and energetics. The work is timely, well-supported by data from the INTERMAGNET network, and its structured analysis from solar wind drivers to latitudinal effects is a significant strength. However, the manuscript would be improved by providing clearer justification for key methodological assumptions, such as the fixed magnetosphere cross-section used in energetics calculations and the specific constants chosen for the Dst* correction. Furthermore, while the storm's repetitive nature is highlighted as unique, the language should be moderated to acknowledge that multi-step storms, though complex, are not unprecedented, and a more explicit linkage between each of the five storm phases and their proposed solar wind drivers (e.g., specific sheath or ejecta regions) would greatly strengthen the physical interpretation. These revisions would enhance the clarity and impact of an otherwise solid and commendable study.