Strong Geomagnetic Storms Research Articles

Simulating Extreme Space Weather With Kinetic Magnetotail Reconnection

AbstractExtreme space weather events require particle‐in‐cell (PIC) modeling to capture the kinetic physics of magnetic reconnection that is not present in magnetohydrodynamic (MHD) models. The MHD with Adaptively Embedded Particle‐In‐Cell (MHD‐AEPIC) model (Chen et al., 2020, https://doi.org/10.1029/2020ea001331) builds on the operational Michigan Geospace space weather model by coupling the FLexible Exascale Kinetic Simulator (FLEKS) PIC code (Chen et al., 2023, https://doi.org/10.1016/j.cpc.2023.108714). The adaptive coupling selects the active PIC domain based on local criteria that identify potential reconnection sites. This saves computational cost compared to large static PIC regions while including full kinetic physics where necessary. Here, the PIC code is activated to follow a flapping plasma sheet and adaptively select areas of potential reconnection. This eliminates the need to constantly cover a huge volume with PIC for the entire simulation timeframe. X. Wang et al. (2022a), https://doi.org/10.1029/2021ja030091 shows the advantages of MHD‐AEPIC in representing local particle distributions in the tail and producing global geomagnetic indices for a strong geomagnetic storm. We build on that work by applying the MHD‐AEPIC model to two extreme geomagnetic storms, the Halloween 2003 and the November 2003 events, to investigate the impact of a kinetic description of tail reconnection for extreme solar wind driving. Adding the PIC code causes dramatic changes in magnetotail magnetic topology and in global geomagnetic indices for these events when compared to ideal MHD. Our simulations with the MHD‐AEPIC model are robust under extreme driving conditions for both events, forming a foundation for exploring hypothetical driving conditions to assess the potential impacts of “worst‐case” storms.

Feasibility analysis of the Doppler index DI in ionospheric scintillation detection at High Arctic region of Canada

Based on data from 16 ISMR stations of Canadian High Arctic Ionospheric Network (CHAIN) this study analyses ionospheric scintillation phenomena during the strong geomagnetic storm on April 23, 2023. The intensity and duration of the geomagnetic storm were confirmed through variations in the Dst and Kp indexes and the global TEC map. The spatiotemporal distribution and correlation of the DI, ROTI and σ φ indexes were analysed, alongside PPP experiments at all stations. The de-trended TEC (dTEC) analysis revealed a link between ionospheric scintillation and TEC fluctuations. Statistical results show a correlation coefficient around 0.7–0.9 between the DI index and ROTI/ σ φ indexes, with consistent spatiotemporal distributions, especially during the main phase of the geomagnetic storms from 9:00 to 21:00 UTC. The DI was also applied to explore the impact of ionospheric scintillation on GPS PPP, where the fluctuations in DI corresponded with increased positioning errors, highlighting its effectiveness as a monitoring tool.

Comparative analysis of two episodes of strongly geoeffective coronal mass ejection events in November and December 2023

In autumn 2023 a series of close-in-time eruptive events were observed remotely and measured in situ. For that period, we studied a set of analogous events on the Sun, where several coronal mass ejections (CMEs) were launched partly from the same (active) regions close to a coronal hole. The two episodes of events are separated by a full solar rotation covering the period October 31 -- November 3 and November 27-- 28, 2023. The two episodes of eruptive events are related to strong geomagnetic storms occurring on November 4--5 and December 1--2, 2023. We point out the complexity for each set of events; our aim is to understand how the global magnetic field configuration, solar wind conditions, and interaction between the structures relate to these geomagnetic effects. We used the graduated cylindrical shell (GCS) 3D reconstruction method to derive the direction of motion and speed of each CME. The GCS results served as input for the drag-based model with enhanced latitudinal information (3D DBM), facilitating the assessment of its connection to in situ measurements. This approach significantly aids in the integrated interpretation of in situ signatures and solar surface structures. The first episode caused visible stable auroral red (SAR) arcs, with a Dst index that dropped in three steps down to -163,nT on November 5, 2023. Close in time, two CME-related shocks arrived, separated by a sector boundary crossing (SBC), and followed by a short-duration flux rope-like structure. For the second episode, auroral lights were observed related to a two-step drop in the Dst index down to -108,nT on December 1, 2023. A shock from a CME within the magnetic structure of another CME ahead was identified, again combined with a SBC. Additionally, a clear flux rope structure from the shock producing CME was detected. In both events, we observed distinct short-term variations in the magnetic field (``ripples'') together with fluctuations in density and temperature that followed the SBC. The study presents a comparative analysis of two episodes of multiple eruptive events in November and December 2023. In addition to the interacting CME structures, we highlight modulation effects in the geomagnetic impact due to magnetic structures that are related to the SBC. These most likely contributed to the stronger geomagnetic impact and production of SAR arcs for the November 4--5, 2023, event. At the Sun, we found the orientation of the heliospheric current sheet to be highly tilted, which might have caused additional effects, due to the CMEs interacting with it.

Significant East‐West Electron Density Differences Occurring in Less Than 30° Longitude Over the Ocean During the Recovery Phase of a Strong Geomagnetic Storm in Solar Minimum

AbstractWe conducted observational studies of ionospheric responses to the geomagnetic storm on 12 May 2021. We selected three cases that the electron density altitude profiles observed by Constellation Observing System for Meteorology, Ionosphere, and Climate‐2 (COSMIC‐2) exhibited significant longitudinal differences in less than 30° longitudes. These cases occurred over the Atlantic Ocean and during the storm's recovery phase. All three cases show relatively weaker variations on the west side between disturbed and quiet time (<10%), while displaying pronounced positive/negative electron density variations on the east side (as large as 100%). GOLD and ICON observations illustrate that the thermospheric composition plays a minor role in the longitudinal differences, while neutral winds and disturbed electric fields make major contributions. Furthermore, significant longitudinal differences in E×B drift and neutral winds have also been observed, which will be part of the future work. This study provides unique insights into ionospheric responses within 30‐degree longitude range over the ocean.

Оценка электронного содержания плазмосферы и высоты перехода O⁺/H⁺ во время геомагнитной бури в феврале 2022 г. по данным Иркутского радара НР

We study the topside ionosphere above the NmF2 ionization maximum and the transition region between the ionosphere and the plasmasphere. We analyze the interaction between the topside ionosphere and the plasmasphere during a strong geomagnetic storm in February 2022, using data from the Irkutsk Incoherent Scatter Radar (IISR) and total electron content data from global navigation satellite systems. To determine the ionosphere and plasmasphere electron contents, an original technique is employed to calculate the integral content of ion density from IISR data, which takes into account the two-component composition of ionospheric plasma. We compare different functions of approximation of the topside ionosphere. The original technique was adjusted for use with IISR Ne data fitted based on the β-Chapman profile. We compare the plasmasphere electron content during quiet and magnetically disturbed days, as well as the dynamics of the O⁺/H⁺ transition height, which is the upper boundary of the ionosphere and the lower boundary of the plasmasphere.

Estimated plasmasphere electron content and O⁺/H⁺ transition height during the February 2022 geomagnetic storm from Irkutsk IS radar data

We study the topside ionosphere above the NmF2 ionization maximum and the transition region between the ionosphere and the plasmasphere. We analyze the interaction between the topside ionosphere and the plasmasphere during a strong geomagnetic storm in February 2022, using data from the Irkutsk Incoherent Scatter Radar (IISR) and total electron content data from global navigation satellite systems. To determine the ionosphere and plasmasphere electron contents, an original technique is employed to calculate the integral content of ion density from IISR data, which takes into account the two-component composition of ionospheric plasma. We compare different functions of approximation of the topside ionosphere. The original technique was adjusted for use with IISR Ne data fitted based on the β-Chapman profile. We compare the plasmasphere electron content during quiet and magnetically disturbed days, as well as the dynamics of the O⁺/H⁺ transition height, which is the upper boundary of the ionosphere and the lower boundary of the plasmasphere.

Magnetic Field Evolution of the Solar Active Region 13664

On 2024 May 10–11, the strongest geomagnetic storm since 2003 November occurred, with a peak Dst index of −412 nT. The storm was caused by NOAA active region (AR) 13664, which was the source of a large number of coronal mass ejections and flares, including 12 X-class flares. Starting from about May 7, AR 13664 showed a steep increase in its size and (free) magnetic energy, along with increased flare activity. In this study, we perform 3D magnetic field extrapolations with the NF2 nonlinear force-free code based on physics-informed neural networks (R. Jarolim et al.). In addition, we introduce the computation of the vector potential to achieve divergence-free solutions. We extrapolate vector magnetograms from the Solar Dynamics Observatory’s Helioseismic and Magnetic Imager at the full 12 minute cadence from 2024 May 5 00:00 to 11 04:36 UT, in order to understand the AR’s magnetic evolution and the large eruptions it produced. A decrease in the calculated relative free magnetic energy can be related to solar flares in ∼90% of the cases, and all considered X-class flares are reflected by a decrease in the relative free magnetic energy. Regions of enhanced free magnetic energy and depleted magnetic energy between the start and end times of major X-class flares show spatial alignment with brightness increases in extreme-ultraviolet observations. We provide a detailed analysis of the X3.9-class flare on May 10, where we show that the interaction between separated magnetic domains is directly linked to major flaring events. With this study, we provide a comprehensive data set of the magnetic evolution of AR 13664 and make it publicly available for further analysis.

Prediction of geomagnetic storms associated with interplanetary coronal mass ejections

Geomagnetic storms have a significant impact on the performance of technical systems both in space and on Earth. The sources of strong geomagnetic storms are most often interplanetary coronal mass ejections (ICMEs), generated by coronal mass ejections (CMEs) in the solar corona. The ICME forecast is based on regular optical observations of the Sun, which make it possible to detect CMEs at the formation stage. It is known that the intensity of geomagnetic storms correlates with the magnitude of the southern component of the magnetic field (Bz) of the ICME. However, it is not possible yet to predict the sign and magnitude ofBzfrom solar observations for the operational forecast of an arbitrary CME. Under these conditions, a preliminary forecast of the magnetic storm probability can be obtained under the assumption that the strength of the storm is related to the magnitude of the magnetic flux from the eruption region, observed as dimming. In this paper we examine the relationship between the integral magnetic flux from the dimming region and the probability that CMEs associated with them will cause geomagnetic storms, using a series of 37 eruptive events in 2010–2012. It is shown that there is a general trend toward an increase in the ICMEs geoefficiency with an increase in the magnitude of the magnetic flux from the dimming region. It has been demonstrated that the frequency of moderate and severe storms observation increases in cases of complex events associated with the interaction of CMEs with other solar wind streams in the heliosphere.

Study of Relationship between Intense Geomagnetic Storms and Halo CME in Solar Cycle 23 and 24

The SOHO/LASCO sensor recorded 53 rapid Earth-directed halo coronal mass ejections (CMEs) from January 2009 to September 2015. According to the statistics, solar flares and CMEs during solar cycle 23 were stronger than during solar cycle 24. An X-class flare's halo coronal mass ejection is one of the solar system's most intense events because of its size, velocity, and strong geomagnetic storms. A total of 86 X-class CMEs were evaluated, with 43% rated as very geoeffective, 28% as moderately so, and 29% as less so. The percentage of storms with geoeffective Ness ranged from 71% in 1996 to 29% in 2019. In cycle 23, there were 78% geoeffective storms; in cycle 24, that number dropped to 56%. Due to the lack of information on the speed of the CME that occurred on December 6, 2006, the study focused on 85 halo CMEs associated with X-class flares. The study found that all types of halo CMEs contribute to the disruption of the Earth's magnetic field, and that 42.18 percent of all CMEs with velocity more than 1000 km/s may cause substantial geomagnetic disturbances.

Investigating the 17 March 2013 Geomagnetic Storm Impacts on the Wholly Coupled Solar Wind‐Magnetosphere‐Ionosphere‐Thermosphere System‐Of‐Systems

AbstractIn this study, we investigate the impacts of the 17 March 2013 strong geomagnetic storm on the wholly coupled Solar Wind‐Magnetosphere‐Ionosphere‐Thermosphere system‐of‐systems. Obtained from multipoint observations, our new results show (1) the solar‐wind Alfven waves propagating antisunward in the sheath region and (2) oscillating solar wind interplanetary magnetic field (IMF) and electric (E) field (IEF EY) that powered (3) rigorous dayside and nightside flux transfer events (FTEs) when (4) the nightside‐reconnection‐related short circuiting led to fast‐time Subauroral Ion Drifts (SAID) and Subauroral Polarization Streams (SAPS) E field development across the inner‐magnetosphere plasmapause where the solar‐wind Alfven waves (4) transitioned into kinetic Alfven waves (5) fueling the hot zone. Also, the antisunward solar‐wind Alfven waves (6) drove enhanced large‐scale region‐1 field‐aligned currents creating (7) undershielding conditions (8) allowing the dawn‐to‐dusk convection E field's earthward penetration, and (9) generated increased solar‐wind kinetic energy, which became deposited (10) to the ionosphere increasing the ionospheric electron temperature (by the downward flowing suprathermal electron fluxes) and (11) to the thermosphere oscillating the neutral winds and increasing the neutral temperature, and finally leading to (12) the development of bright stable auroral red (SAR) arcs in (13) the enhanced SAID/SAPS flow channels (FCs) developed during FTEs, (14) demonstrated with FC‐2 and FC‐3 events, in the enhanced polar convection that (15) the Rice Convection Model could reproduce. Finally, we conclude the antisunward‐propagating large‐amplitude solar‐wind Alfven waves' ultimate significant role in creating the favorable conditions for the various phenomena documented with the new observational results (1–14).

Parameter Study of Geoeffective Active Regions

Geomagnetic storms (GSs) are major disturbances in the terrestrial atmosphere caused by the reconnection process between the incoming plasma ejecta in the solar wind and the planetary magnetosphere. The strongest GSs can lead to auroral displays even at lower latitudes, and cause both satellite and ground-based infrastructure malfunctions. The early recognition of geoeffective events based on specific features on the solar photosphere is crucial for the development of early warning systems. In this study, we explore 16 magnetic field parameters provided by the Space-weather HMI Active Region Patch (SHARP) database from the SDO/HMI instrument. The analysis includes 64 active regions that produced strong GS during solar cycle (SC) 24 and the ongoing SC25. We present the statistical results between the SHARP and solar parameters, in terms of Pearson and Spearman correlation coefficients, and discuss their space weather potential.

Establishment and Application of an Interplanetary Disturbance Index Based on the Solar Wind–Magnetosphere Energy Coupling Function and the Spectral Whitening Method

We develop a preliminary interplanetary disturbance index (J sW ) by applying the spectral whitening method to an energy coupling function with solar wind measurements during the years 1998–2014 as the input, which can be used as an indicator of perturbations in the near-Earth solar wind. The correlation and temporal variation between J sW and the geomagnetic disturbance index (J pG ) constructed from the same method have been analyzed in detail for 167 geomagnetic storms with the minimum D st index less than or equal to −50 nT. The time delay between J sW and J pG is clearly observable and varies for different events, according to which J sW is shifted backward with respect to J pG . We obtain a fairly good negative correlation between the shifted J sW and the J pG indices for the majority of events, and the significance level for 88% of the events (i.e., 147 events) does not exceed 0.05. A statistical analysis of the shifted J sW and the J pG indices for 147 selected events reveals that larger values of J sW and smaller magnitudes of J pG are commonly accompanied by enhanced southward magnetic fields, which implies that more solar wind energy is entering the magnetosphere and thus causing strong geomagnetic storms. Furthermore, a linear fit of the two indices suggests that the evolution of J pG can be predicted about 2 hr in advance based on J sW , indicating that J sW can provide early warnings of possible disturbances in the geomagnetic fields, which is crucial for space weather monitoring and operational forecasting.

New Anisotropic Cosmic-Ray Enhancement (ACRE) Event on 5 November 2023 Due to Complex Heliospheric Conditions

The variability of galactic cosmic rays near Earth is nearly isotropic and driven by large-scale heliospheric modulation but rarely can very local anisotropic events be observed in low-energy cosmic rays. These anisotropic cosmic-ray enhancement (ACRE) events are related to interplanetary transients. Until now, two such events have been known. Here, we report the discovery of the third ACRE event observed as an increase of up to 6.4% in count rates of high- and midlatitude neutron monitors between ca. 09 – 14 UT on 5 November 2023 followed by a moderate Forbush decrease and a strong geomagnetic storm. This is the first known observation of ACRE in the midrigidity range of up to 8 GV. The anisotropy axis of ACRE was in the nearly anti-Sun direction. Modeling of the geomagnetic conditions implies that the observed increase was not caused by a storm-induced weakening of the geomagnetic shielding. As suggested by a detailed analysis and qualitative modeling using the EUHFORIA model, the ACRE event was likely produced by the scattering of cosmic rays on an intense interplanetary flux rope propagating north of the Earth and causing a glancing encounter. The forthcoming Forbush decrease was caused by an interplanetary coronal mass ejection that hit Earth centrally. A comprehensive analysis of the ACRE and complex heliospheric conditions is presented. However, a full quantitative modeling of such a complex event is not possible even with the most advanced models and calls for further developments.

Dynamics and solar wind control of the recovery of strong geomagnetic storms

Dynamics and solar wind control of the recovery of strong geomagnetic storms

A Statistical Analysis of the Morphology of Storm‐Enhanced Density Plumes Over the North American Sector

AbstractThe storm‐enhanced density (SED) is a large‐scale midlatitude ionospheric electron density enhancement in the local afternoon sector, which exhibits substantial spatial gradients and thus can impose detrimental effects on modern navigation and communication systems, causing potential space weather hazards. This study has identified a comprehensive list of 49 SED events over the continental US and adjacent regions, by examining strong geomagnetic storms occurring between 2000 and 2023. The ground‐based Global Navigation Satellite System (GNSS) total electron content and data from a new TEC‐based ionospheric data assimilation system were used to analyze the characteristics of SED. For each derived SED events, we have quantified its morphology by employing a Gaussian function to parameterize key characteristics of the SED, such as the plume intensity, central longitude, and half‐width. A statistical analysis of SEDs was conducted for the first time to characterize their climatological features. We found that the SED distribution exhibits a higher peak intensity and a narrower width as geomagnetic activity strengthens. The peak intensity of SED has maximum values around the equinoxes in their seasonal distribution. Additionally, we observed a solar cycle dependence in the SED distribution, with more events occurring during the solar maximum and declining phases compared to the solar minimum. SED plumes exhibit a sub‐corotation feature with respect to the Earth, characterized by a westward drift speed between 50 and 400 m/s and a duration of 3–10 hr. These information advanced the current understanding of the spatial‐temporal variation of SED characteristics.

3‐D Ionospheric Imaging Over the South American Region With a New TEC‐Based Ionospheric Data Assimilation System (TIDAS‐SA)

AbstractThis study has developed a new TEC‐based ionospheric data assimilation system for 3‐D regional ionospheric imaging over the South American sector (TIDAS‐SA) (45°S–15°N, 35°–85°W, and 100–800 km). The TIDAS‐SA data assimilation system utilizes a hybrid Ensemble‐Variational approach to incorporate a diverse set of ionospheric data sources, including dense ground‐based Global Navigation Satellite System (GNSS) line‐of‐sight Total Electron Content (TEC) data, radio occultation data from the Constellation Observing System for Meteorology, Ionosphere, and Climate‐2 (COSMIC‐2), and altimeter TEC data from the JASON‐3 satellite. TIDAS‐SA can produce a reanalyzed three‐dimensional (3‐D) electron density spatial variation with a high time cadence, yielding spatial‐temporal resolution of 1° (latitude) × 1° (longitude) × 20 km (altitude) × 5 min. This allows us to reconstruct and study the 3‐D ionospheric morphology with multi‐scale structures. The performance of the data assimilation system is validated against independent ionosonde and in situ measurements through an experiment for a strong geomagnetic storm event on 03–04 November 2021. The results demonstrate that TIDAS‐SA can provide detailed and altitude‐resolved information that accurately characterizes the storm‐time ionospheric disturbances in vertical and horizontal domains over the equatorial and low‐latitude regions of South America.

Investigating the heliosphere, magnetosphere, atmosphere, and properties of cosmic rays during the 2018 Aug 25–26 strong geomagnetic storm

Investigating the heliosphere, magnetosphere, atmosphere, and properties of cosmic rays during the 2018 Aug 25–26 strong geomagnetic storm

ON THE DELAY OF THE ADDITIONAL MORTALITY LINKED TO THE GEOMAGNETIC DISTURBANCES

The geomagnetic disturbances, mainly geomagnetic storms (GMSs), but also low frequency resonances, touch some people susceptible to cerebrovascular diseases (CVDs). Sometimes the geomagnetic effect is overestimating speculatively. Against this concept we compare the changes of geomagnetic indexes (GMIs) with the changes of additional mortality rate (AMR). We compare by means of cross-correlation functions (CCFs) and use the Wolf number (WN) as referent time scale. We suspect that strong GMSs, like these in 2003, increase the relative common MR 3–4 years later with up to 4×10-5. Otherwise, the typical GMS linked AMR seems to be less than 10-5. Even if these values are overestimated, generally they are small. Analyzing data about Bulgaria and 5 its regions for the last solar cycles, we confirm that the lag of the maxima of the GMS linked ANR behind the WN maxima is ~5 years. We confirm also that the lag of the GMSs maxima behind the WN maximum is 1–2 years. Especially, we found that the lag of the maxima of the CVD linked AMR behind the maxima of the GMSs is 3–4 years. So, we consider the 5 years lag of the AMR linked to the GMSs behind the WN maximum appears a sum of two above mentioned delays, 1–2 years and 3–4 years. In principle, the typical duration of CVDs may be derived if the beginnings are known. In the medicine they are usually unknown. However, suspecting the GMSs as triggers of a part of the CWD linked AMR, we should suppose that these CWDs finish with lethal outcome after 3–4 years.

Spatiotemporal characteristics of the December 1, 2023 geomagnetic storm on data from the NHC optical complex and the Irkutsk Regional Astronomical Society

The results of the December 1, 2023 strong geomagnetic storm studies are presented using images from citizen scientists in the Irkutsk region. Based on the method of frames georeferencing and stereometry, the spatial parameters of mid-latitude auroras were determined. The prospect of joint use of citizen scientists photographs and specialized optical instruments data for studying geomagnetic storms is discussed.

Changes in the energy density of the Earth's magnetic field at the PIA, Slovenia, observatory during the G5 Geomagnetic Storm on May 11, 2024

Geomagnetic storms are the largest disturbance in the Earth's magnetic field. On May 11, 2024, a geomagnetic storm occurred at the peak of the 25th solar cycle, reaching the highest level (G5) on the planetary scale. On that day, a geomagnetic storm was also measured at the PIA geomagnetic observatory (Piran, Slovenia), reaching the maximum possible value of the geomagnetic index K = 9. Such strong geomagnetic storms occur on average every 40 to 60 years. A geomagnetic storm with an index of K = 9 represents an important reference for all disturbances in the local magnetic field from different sources and different intensities. Therefore, an analysis of accelerations in the energy density of the local magnetic field during the first 150 days in 2024 was made. The identified effects of geomagnetic storms with different K indices will serve to better analyse disturbances in the local magnetic field that have occurred in the past years and will happen in the future.