Halo Coronal Mass Ejections Research Articles

What Do Halo CMEs Tell Us about Solar Cycle 25?

It is known that the weak state of the heliosphere due to diminished solar activity in cycle 24 backreacted on coronal mass ejections (CMEs) to make them appear wider for a given speed. One of the consequences of the weak state of the heliosphere is that more CMEs appear as halo CMEs (HCMEs), and halos are formed at shorter heliocentric distances. Current predictions for the strength of solar cycle (SC) 25 range from half to twice the strength of SC 24. We compare the HCME occurrence rate and other properties during the rise phase of cycles 23, 24, and 25 to weigh in on the strength of SC 25. We find that HCME and solar wind properties in SC 25 are intermediate between SCs 23 and 24, but closer to SC 24. The HCME occurrence rate, normalized to the sunspot number, is higher in SCs 24 and 25 than in SC 23. The solar wind total pressure in SC 25 is ∼35% smaller than that in SC 23. Furthermore, the occurrence rates of high-energy solar energetic particle events and intense geomagnetic storms are well below the corresponding values in SC 23, but similar to those in SC 24. We conclude that cycle 25 is likely to be similar to or slightly stronger than cycle 24, in agreement with polar-field precursor methods for cycle 25 prediction.

An analysis of slow drift type II radio burst and its association with full halo coronal mass ejection on 12th January 2022

Radio bursts have been a point of contention among astrophysicists in the modern era. Solar flares, coronal mass ejections (CMEs), and solar energetic particles (SEPs) that project from the Sun to interplanetary space can all be observed using this method. Based on data from e-Callisto, we detected a type II radio burst on 12th January 2022 starting at 04:24 UT and lasting until 04:56 UT. The full image of radio burst type II (SRBTII) was compiled from two stations (Almaty and Australia-ASSA), the drift rate of the bursts calculated are -0.07796 MHz/s and - 0.105822893 MHz/s respectively, and the relevant solar activity was determined. There was a possible association between the observed burst and the halo CME event on the day. This study includes the properties of the CME and the D-region Absorption Prediction (D-Rap) plot as the signal degradation indicator caused by the solar flare and CMEs to demonstrate its significance in understanding the impact on Earth’s atmosphere.

Solar active region magnetic parameters and their relationship with the properties of halo coronal mass ejections

The coronal mass ejections (CMEs) from the sun consist of the plasma and strong magnetic fields (∼4–5 G at 1.3 R⊙) and generally, the fast CMEs are often associated with energetic particles of energy few hundreds of MeV. When the fast CMEs are ejected towards the Earth, they can disrupt the flow of solar wind in the heliosphere and impact the Earth's magnetosphere causing known space weather phenomena such as, geomagnetic storms, auroras, communication blackouts, satellite drag and failures. In this work, we have investigated a set of 60 halo coronal mass ejections (CMEs) associated with X-ray flares (≥C1.0) observed in 49 active regions during the period 2010–2016 in solar cycle 24. The X-ray flares and white light CMEs were observed by Geostationary Operational Environmental Satellite (GOES) and the Large Angle Spectrometric Coronagraph (LASCO) coronagraph on the Solar and Heliospheric Observatory (SOHO) satellite, respectively. The active region magnetic properties are obtained from Space - weather HMI Active Region Patch (SHARP) parameters for this set of events. For each active region (AR), the mean value is calculated from a 1-day time series for each of the 16 photospheric magnetic parameters extracted from the vector magnetogram products at a 12-min cadence. The dependency of flare flux and CME kinematics properties on the active region magnetic properties is further confirmed through correlation studies. As a result, we found a moderate to strong correlation value for flare flux and halo CME kinematic properties (like linear speed, space speed and kinetic energy) among the seven (USFLUX, TOTUSJZ, TOTUSJH, ABSNJZH, SAVNCPP, TOTPOT and MEANJZH) SHARP parameters. Most of the events (≥73%) were produced by βγδ, βγ and βδ Hale - type sunspot groups and Ekc/Dkc/Fkc McIntosh sunspot classes. It reveals that the most complex active regions are feasible sources of strong flare-associated halo CME productivity. The front side halo CME kinematic properties depend more on the vertical current helicity and polarity magnetic parameters than the other magnetic parameters. In addition, the flare intensity and speed of CME, calculated using an empirical model with the active region magnetic parameters, are found nearly equal to the observed values. This result will be useful to identify the important magnetic parameters for modelling the occurrence of flare-associated halo CMEs and to understand the physical relationship between them.

Forecasting the transit times of earth-directed halo CMEs using artificial neural network: A case study application with GCS forward-modeling technique

Mitigating the lethal threats caused by coronal mass ejections (CMEs) on human and space operations can be accomplished with a fast and accurate forecast of Earth-directed CME transit times. The current paper presents a robust Cascade Forward Neural Network (CFNN) framework to predict the transit times of Earth-directed halo CMEs using a total of 290 CME/Interplanetary coronal mass ejections (ICME) pairs of datasets for the past two and half decades (solar cycle; SC 23, 24, 25). It is the first time incorporating deprojected speeds into a machine learning framework to mitigate uncertainties due to projection effects during CME transit time prediction. The CFNN model forecasted the transit times of 87 Earth-directed CMEs and recorded a mean absolute error (MAE) of 7.3 h. In addition, 5 selected fast-moving (energetic) halo CME episodes during the deep phases (solar minima) of SC 25 were reconstructed using the Graduated Cylindrical Shell (GCS) forward-modeling technique. The events were predicted using the CFNN model (MAE = 4.5 h) in comparison with the Drag-Based model (DBM; MAE = 6.2 h) and Empirical Shock Arrival model (ESA; MAE = 13.5 h) to evaluate the robustness and the flexibility of the CFNN framework as well as the reliability of the CME 3D speed as a proxy for the space speed. The CFNN framework demonstrated satisfactory performance in contrast to previously used models by minimizing CME arrival time prediction errors due to projection effects. Hence, the study validated the efficiency of the GCS model for studying the 3D kinematics of CMEs and emphasized the essence of utilizing deprojected speeds in machine learning frameworks as better alternatives for fast, reliable, and accurate CME arrival (transit) time predictions.

L1 and Off Sun‐Earth Line Visible‐Light Imaging of Earth‐Directed CMEs: An Analysis of Inconsistent Observations

AbstractThe efficacy of coronal mass ejection (CME) observations as a key input to space weather forecasting is explored by comparing on and off Sun‐Earth line observations from the ESA/NASA SOHO and NASA STEREO spacecraft. A comparison is made of CME catalogs based on L1 coronagraph imagery and off Sun‐Earth line coronagraph and heliospheric imager observations, for the year 2011. Analysis reveals inconsistencies in the identification of a number of potentially Earth‐directed CMEs. The catalogs reflect our ability to identify and characterize CMEs, so any discrepancies can impact our prediction of Earth‐directed CMEs. We show that 15 CMEs, which were observed by STEREO, that had estimated directions compatible with Earth‐directed events, had no identified halo/partial halo counterpart listed in the L1 coronagraph CME catalog. In situ data confirms that for 9 of these there was a consistent L1 Interplanetary CME (ICME). The number of such “discrepant” events is significant compared to the number of ICMEs recorded at L1 in 2011, stressing the need to address space weather monitoring capabilities, particularly with the inclusion of off Sun‐Earth line observation. While the study provides evidence that some halo CMEs are simply not visible in near‐Earth coronagraph imagery, there is evidence that some halo CMEs viewed from L1 are compromised by preceding CME remnants or the presence of multiple‐CMEs. This underlines (a) the value of multiple vantage point CME observation, and (b) the benefit of off Sun‐Earth line platform heliospheric imaging, and coronagraph imaging, for the efficient identification and tracking of Earth‐directed events.

Characteristics of Different Groups of Flare-CME in the Minimum to Rising Phase of Solar Cycle 24

Coronal Mass Ejections are significant solar events that involve intense explosions of magnetic fields and mass particles out from the corona. As the hot plasma are brought by the solar wind into the Earth’s magnetosphere, geomagnetic storm is generated and causing malfunctions in telecommunication and power systems. This study is aimed to investigate the distribution of flare-CMEs characteristics which occurred at the beginning phase of solar cycle 24, from Dec. 2008 until Dec. 2013. In the analysis, all events are classified according to their class of flares associated with the CMEs. The CMEs that are accompanied by A, B, and C flares are categorized as low group flare-CME, while CMEs with M and X flares are placed under high group flare-CME. Afterwards, they are analyzed to observe the distribution of their main CME properties; velocity, acceleration and angular width. At the end of the study, we found that velocity and angular width are the two properties that have high influential for high and low groups, with R value of 0.36 and 0.67, respectively. Most of high group flare-CMEs showed up in 360° as well as low group flare-CMEs if the associated minor flares lasted longer than 30 min. Furthermore, the speed range of 360° high and low class flare-CME cannot be defined from the results since all of them propagated at fluctuating velocity. Hence, it is believed that full halo CMEs have no velocity boundary as they can travel from 500 km/s and go beyond 2500 km/s.

Analysis of Geoeffective Impulsive Events on the Sun During the First Half of Solar Cycle 24

A coronal mass ejection (CME) is an impulsive event that emerges rapidly from the Sun. We observed a quiet Sun without many spectacular episodes during the last decade. Although some fast halo and partial halo CMEs had taken place, among them was the backside CME on 23 July 2012. In this work, we verify the link between the variability of solar-wind, heliospheric and geomagnetic parameters and the transmission grid failures registered in southern Poland during 2010 – 2014 when many geomagnetic storms appeared, caused by halo and partial halo CMEs. We aim to apply three machine learning methods: Principal Components Analysis, Self-Organizing Maps, and Hierarchical Agglomerative Clustering to analyze sources on the Sun and the impacts of the intense geomagnetic storms in the first half of Solar Cycle 24. The conducted analyzes underline the importance of solar-wind proton temperature and point out other solar-wind and geomagnetic parameters independently indicated by all the methods used in this study.

Analysis of Front Side Halo CMEs and Their Solar Source Active Region and Flare Ribbon Properties

Analysis of Front Side Halo CMEs and Their Solar Source Active Region and Flare Ribbon Properties

On the detection of a solar radio burst event that occurred on 28 August 2022 and its effect on GNSS signals as observed by ionospheric scintillation monitors distributed over the American sector

As part of an effort to observe and study ionospheric disturbances and their effects on radio signals used by Global Navigation Satellite Systems (GNSS), alternative low-cost GNSS-based ionospheric scintillation and total electron content (TEC) monitors have been deployed over the American sector. During an inspection of the observations made on 28 August 2022, we found increases in the amplitude scintillation index (S4) reported by the monitors for the period between approximately 17:45 UT and 18:20 UT. The distributed, dual-frequency observations made by the sensors allowed us to determine that the increases in S4were not caused by ionospheric irregularities. Instead, they resulted from Carrier-to-Noise (C/No) variations caused by a solar radio burst (SRB) event that followed the occurrence of two M-class X-ray solar flares and a Halo coronal mass ejection. The measurements also allowed us to quantify the impact of the SRB on GNSS signals. The observations show that the SRB caused maximum C/No fadings of about 8 dB-Hz (12 dB-Hz) on L1 ~ 1.6 GHz (L2 ~ 1.2 GHz) for signals observed by the monitor in Dallas for which the solar zenith angle was minimum (~24.4°) during the SRB. Calculations using observations made by the distributed monitors also show excellent agreement for estimates of the maximum (vertical equivalent) C/No fadings in both L1 and L2. The calculations show maximum fadings of 9 dB-Hz for L1 and of 13 dB-Hz for L2. Finally, the results exemplify the usefulness of low-cost monitors for studies beyond those associated with ionospheric irregularities and scintillation.

A Study on the Geoeffectiveness of Halo Coronal Mass Ejections During the Period of 1996- 2018

In this study, we investigate the solar origins and interplanetary properties of 83 geoeffective halo coronal mass ejections (CMEs) that produced intense geomagnetic storms (Dst ≤ -100 nT) on Earth, spanning the time interval from 1996 to 2018, which includes solar cycles 23 and 24. Observations indicate that full-halo CMEs are potential contributors to intense geomagnetic activity on Earth. However, it is worth noting that not all full-halo CMEs lead to significant geomagnetic storms, which adds complexity to the task of space weather forecasting. Our investigation delves into the solar origins and flare connections of these geoeffective CMEs and their interplanetary effects, specifically, solar wind speed, and the southward component of the interplanetary magnetic field Bz. The objective is to elucidate the relationship between solar and interplanetary parameters. Specifically, this study aims to identify solar parameters that govern key interplanetary parameters responsible for generating significant geomagnetic storms. Our findings indicate that fast full-halo CMEs, associated with powerful flares and originating from favourable locations (i.e., near the central meridian and at low to mid latitudes), are the most likely candidates for producing intense geomagnetic storms. Additionally, our results demonstrate that the intensity of geomagnetic storms is most strongly influenced by the southward component of the interplanetary magnetic field, but is less dependent on the initial speed of the CME.

Observational evidence of thermospheric wind and composition changes and the resulting ionospheric disturbances in the European sector during extreme geomagnetic storms

On November 1st and 2nd, 2021, four Halo coronal mass ejections were ejected from the Sun, releasing billions of tons of high-energy particles into interplanetary space. These were directed towards the Earth and reached our planet on November 3rd and 4th, 2021, generating the first G3-level extreme geomagnetic storm since the beginning of the 25th solar cycle. In this study, we investigate the thermospheric and ionospheric responses in the European sector to a G3-level storm using various observational data from Fabry-Perot interferometer, Ionospheric Connection Explorer/Michelson Interferometer for Global High-resolution Thermospheric Imaging (ICON/MIGHTI), and Thermosphere Ionosphere Mesosphere Energetics and Dynamics/Global Ultraviolet Imager (TIMED/GUVI). The results show positive ionospheric storms in the middle and low latitudes of Europe which may be associated with the equatorward and westward neutral winds induced by heating in the polar region. In contrast, negative storms were detected at high latitudes in association with the increase in thermospheric density (upwelling). These two antithetical responses were confirmed by using European ionosonde and total electron contents (TEC) observation chains distributed over a wide range of latitudes. Finally, we, for the first time, attempt to identify the imaginary boundary line between the two responses.

The first gradual solar energetic particle event with an enhanced 3He abundance on Solar Orbiter

The origin of 3He abundance enhancements in gradual solar energetic particle (SEP) events remains largely unexplained. Two mechanisms have been suggested: the reacceleration of remnant flare material by coronal mass ejection (CME)-driven shocks in interplanetary space, and concomitant activity in the corona. We explore the first gradual SEP event with enhanced 3He abundance that was observed by Solar Orbiter. The event started on 2020 November 24 and was associated with a relatively fast halo CME. During the event, the spacecraft was at 0.9 au from the Sun. The event-averaged 3He/4He abundance ratio is 24 times higher than the coronal or solar wind value, and the timing of the 3He intensity was similar to that of other species. We inspected available imaging, radio observations, and the spacecraft magnetic connection to the CME source. The most probable cause of the enhanced 3He abundance apparently are residual 3He ions remaining from a preceding long period of 3He-rich SEPs on 2020 November 17–23.

Relationships between energetic storm particle events and interplanetary shocks driven by full and partial halo coronal mass ejections

We have analysed energetic storm particle (ESP) events in 116 interplanetary (IP) shocks driven by front-side full and partial halo coronal mass ejections (CMEs) with speeds >400 kms−1during the years 1996–2015. We investigated the occurrence and relationships of ESP events with several parameters describing the IP shocks, and the associated CMEs, type II radio bursts, and solar energetic particle (SEP) events. Most of the shocks (57%) were associated with an ESP event at proton energies >1 MeV.The shock transit speeds from the Sun to 1 AU of the shocks associated with an ESP event were significantly greater than those of the shocks without an ESP event, and best distinguished these two groups of shocks from each other. The occurrence and maximum intensity of the ESP events also had the strongest dependence on the shock transit speed compared to the other parameters investigated. The correlation coefficient between ESP peak intensities and shock transit speeds was highest (0.73 ± 0.04) at 6.2 MeV. Weaker dependences were found on the shock speed at 1 AU, Alfvénic and magnetosonic Mach numbers, shock compression ratio, and CME speed. On average all these parameters were significantly different for shocks capable to accelerate ESPs compared to shocks not associated with ESPs, while the differences in the shock normal angle and in the width and longitude of the CMEs were insignificant.The CME-driven shocks producing energetic decametric–hectometric (DH) type II radio bursts and high-intensity SEP events proved to produce also more frequently ESP events with larger particle flux enhancements than other shocks. Together with the shock transit speed, the characteristics of solar DH type II radio bursts and SEP events play an important role in the occurrence and maximum intensity of ESP events at 1 AU.

Automated Detection of coronaL MAss Ejecta origiNs for Space Weather AppliCations (ALMANAC)

AbstractAlerts of potentially hazardous coronal mass ejection (CME) are based on the detection of rapid changes in remote observations of the solar atmosphere. This paper presents a method that detects and estimates the central coordinates of CME eruptions in Extreme Ultraviolet data, with the dual aim of providing an early alert, and giving an initial estimate of the CME direction of propagation to a CME geometrical model. In particular, we plan to link the Automated detection of coronaL MAss ejecta origiNs for space weather AppliCations (ALMANAC) method to the CME detection and characterization module of the Space Weather Empirical Ensemble Package, which is a fully automated modular software package for operational space weather capability currently being developed for the UK Meteorological Office. In this work, ALMANAC is applied to observations by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO). As well as presenting the method, a proof of concept test is made on a limited set of data associated with 20 halo CMEs recorded by the Coordinated Data Analysis Workshop (CDAW) catalog near the activity maximum of solar cycle 24. SDO/AIA data for each event is processed at 6 min cadence to identify the on‐disk location and time of each CME. The absolute mean deviance between the ALMANAC and CDAW source event coordinates are within 37.05 ± 29.71 min and 11.01 ± 10.39°. These promising results give a solid foundation for future work, and will provide initial constraints to an automated CME alert and forecasting system.

The State of the White-Light Corona over the Minimum and Ascending Phases of Solar Cycle 25 – Comparison with Past Cycles

We report on the state of the corona over the minimum and ascending phases of Solar Cycle (SC) 25 on the basis of the temporal evolutions of its radiance and of the properties of coronal mass ejections (CMEs), as determined from white-light observations performed by the SOHO/LASCO-C2 coronagraph. These evolutions are further compared with those determined during the past two Solar Cycles using the same methods. The integrated radiance of the K-corona and the occurrence rate of CMEs closely track the indices/proxies of solar activity, prominently the total magnetic field for the radiance and the 10.7 cm radio flux for the CMEs, all undergoing a steep increase during the ascending phase of SC 25. This increase is much steeper than anticipated on the basis of the predicted quasi-similarity between SC 25 and SC 24, and is confirmed by the recent evolution of the sunspot number. The radiance reached the same base level during the minima of SC 24 and SC 25, but the latitudinal extent of the streamer belt differed, being flatter during the latter minimum and in fact more similar to that of the minimum of SC 23. Synchronizing the descending branches of SC 23 and SC 24 led to a duration of SC 24 of 11.0 years, similar to that given by the sunspot number. In contrast, the base level of the occurrence rate of CMEs during the minimum of SC 25 was significantly larger than during the two previous minima. The southern hemisphere is conspicuously more active than the northern, in agreement with several predictions and the current evolution of the hemispheric sunspot numbers. In particular, the occurrence rate of the subset of CMEs with known mass, their mass rate, and the number of CMEs with speeds larger than 350 km s−1 in the southern hemisphere exceeds by far the respective values in the northern hemisphere. The mean apparent width of CMEs and the number of halo CMEs remains at relatively large, constant levels throughout the early phase of SC 25, implying the persistence of weak total pressure in the heliosphere. These results, and particularly the perspective of a corona being more active than anticipated, are extremely promising for the forthcoming observations by both Solar Orbiter and Parker Solar Probe.

A Double-decker Filament Formation Driven by Sunspot Rotation and Magnetic Reconnection

In this paper, through analyzing data from the Solar Dynamics Observatory (SDO) and the Global Oscillation Network Group (GONG), we present a study on the formation of a double-decker filament in NOAA Active Region 12665 from 2017 July 8 to 14. We find that magnetic reconnection occurs between two smaller filaments to form a longer filament. According to the evolution of the leading sunspot, it is obvious that the sunspot experiences a continuous rotation around its umbra. During the period from 03:00 UT on July 11 to 10:00 UT on July 14, the average speed of sunspot rotation is about 3.°7 hr–1. The continuous rotation of sunspot stretches the filament and results in the formation of a reversed S-shaped filament. Due to the motion of the magnetic field and internal magnetic reconnection, the filament splits into two branches and forms a double-decker filament structure. In the process of filament separation, internal magnetic reconnection can also accelerate the filament separation. Nonlinear force-free field extrapolation indicates that there are two magnetic flux ropes, which are consistent with the observed results. Eventually, the upper filament erupts and produces an M-class flare and a halo coronal mass ejection.

Effects of Solar Proton Events Associated With X-Ray Flares on Near-Earth Electron and Proton Fluxes Based on ZH-1 Satellite Observations

Solar eruptions can cause violent effects on the space environment. Electromagnetic radiation from solar flares will be the first to arrive on the Earth at the speed of light, followed by solar energetic charged particles. The last to appear will be coronal mass ejections and geomagnetic storms. Based on observations of ZH-1 satellite, we report three strong disturbed space environment events, all of them with solar proton events (SPEs), and analyze the driving mechanisms: 1) On 29 November 2020, an M4.4 flare accompanied with a full halo CME caused a gradual SPE, which was mainly driven by CME shocks. 2) On 28 May 2021, a C9.4 flare brought an impulsive SPE, which was accelerated by the flare. The heliolongitude of this small flare was 63°W, near the footpoint of the magnetic field line leading from the Sun to the Earth. 3) On 28 October 2021, a full-halo CME accompanied with an X1.1 flare brought a gradual SPE. On 2 November 2021, another fast full halo CME accompanied with flare was ejected. The faster CME of November 2 caught up and swept up the slower CME of November 1, and subsequently caused a severe geomagnetic storm (minimum Dst = -101) and a high-energy electron storm on November 4. The observations of the above three space environmental events confirm that the data quality of the high-energy particle package (HEPP) from ZH-1 is highly reliable and accurate and is highly advantageous to monitoring the variation of energetic particles and X-rays in the radiation belt of the Earth during solar activities.

Triggering Mechanism for Eruption of Two Filaments Observed by the Solar Dynamics Observatory, Nobeyama Radioheliograph, and RHESSI

We investigate the eruptive process of two filaments, which is associated with an M-class flare that occurred in 2011 August 4. The filaments are partly overlapped, one in the active region and the other just beside it, and erupt together as a halo coronal mass ejection. For this study, we used the Atmospheric Imaging Assembly and the Heliospheric Magnetic Imager on board the Solar Dynamics Observatory, the Nobeyama Radioheliograph 17 GHz, and the RHESSI Hard X-ray satellite. We found three distinct phases in the microwave flux profile and in the rising pattern of the filaments during the event. In the first phase, there was weak nonthermal emission at 17 GHz and hard X-rays. Those nonthermal sources appeared on one edge of the western filament (F2) in the active region. The F2 began to be bright and rose upward rapidly, while the eastern filament (F1), which was extended to the quiet region, started to brighten from the peak time of the 17 GHz flux. In the second phase, the nonthermal emission weakened and the F2 rose up slowly, while the F1 began to rise up. In the third phase, two filaments erupted together. Since the F1 was stable for a long time in the quiet region, breaking the equilibrium state of the F1 would be decisive for the successful eruption of two filaments and it seems clear that the evolution of the F2 provoked the unstable F1. We suggest that tether-cutting reconnection between two overlapped filaments triggers the eruption of the two filaments as a tangled identity.

The Study of Geomagnetic Activity from 2017 to 2020 Period

Geomagnetic storm has been extensively studied and observed because it can interfere satellite and radio communications. Some parameters, such as Dst index, Kp index, north-south interplanetary magnetic field (Bz) and speed of solar wind (Vsw), can be used to identify the level of geomagnetic storm and assess its potential risk. Therefore, this paper provides the analysis of geomagnetic parameters and their correlation to geomagnetic activities during 2017-2020 period. The geomagnetic data, i.e. Dst, Kp, Bz, and Vsw, were obtained from the website: https://omniweb.gsfc.nasa.gov. The results indicated that some significant geomagnetic storms occurred during 2017-2020, which were shown by the sharp increase of the Dst index, which was also followed by the increase of Kp index, the increase of Vsw, and the extreme fluctuations of Bz index. Three big events occurred on May 28th 2017, September 8th 2017, and August 26th 2018, which had the Dst increase to as high as -125 nT, -124 nT, and -174 nT (< -100 nT), respectively, followed by seventeen minor storm events with Dst between -45 nT until -76 nT. The geomagnetic storm events were probably driven by earth-directed coronal mass ejection (CME) or halo CMEs or high-speed solar wind flows from coronal holes. This result was also supported with the data of flux electron detected at outer radiation belt that have been increased. It can be concluded that the north-south interplanetary magnetic field (Bz) and speed of solar wind (Vsw) have a strong correlation to geomagnetic storm events in which the increasing of Bz followed the increasing of Vsw.

Implementation and validation of the FRi3D flux rope model in EUHFORIA

The “Flux Rope in 3D” (FRi3D, Isavnin, 2016), a coronal mass ejection (CME) model with global three-dimensional (3D) geometry, has been implemented in the space weather forecasting tool EUHFORIA (Pomoell and Poedts, 2018). By incorporating this advanced flux rope model in EUHFORIA, we aim to improve the modelling of CME flank encounters and, most importantly, the magnetic field predictions at Earth. After using synthetic events to showcase FRi3D’s capabilities of modelling CME flanks, we optimize the model to run robust simulations of real events and test its predictive capabilities. We perform observation-based modelling of the halo CME event that erupted on 12 July 2012. The geometrical input parameters are constrained using the forward modelling tool included in FRi3D with additional flux rope geometry flexibilities as compared to the pre-existing models. The magnetic field input parameters are derived using the differential evolution algorithm to fit FRi3D parameters to the in situ data at 1 AU. An observation-based approach to constrain the density of CMEs is adopted, in order to achieve a better estimation of mass corresponding to the FRi3D geometry. The CME is evolved in EUHFORIA’s heliospheric domain and a comparison of FRi3D’s predictive performance with the previously implemented spheromak CME in EUHFORIA is presented. For this event, FRi3D improves the modelling of the total magnetic field magnitude and Bz at Earth by ∼30% and ∼70%, respectively. Moreover, we compute the expected geoeffectiveness of the storm at Earth using an empirical Dst model and find that the FRi3D model improves the predictions of minimum Dst by ∼20% as compared to the spheromak CME model. Finally, we discuss the limitations of the current implementation of FRi3D in EUHFORIA and propose possible improvements.