Storms Of Solar Cycle Research Articles

Understanding Strong Neutral Vertical Winds and Ionospheric Responses to the 2015 St. Patrick's Day Storm Using TIEGCM Driven by Data‐Assimilated Aurora and Electric Fields

AbstractAs one of the strongest geomagnetic storms in Solar Cycle 24, the 2015 St. Patrick's Day storm has attracted significant attention. We revisit this event by taking advantage of simultaneous observations of high‐latitude forcings (aurora and electric fields) and ionosphere‐thermosphere (I‐T) responses. The forcing terms are assimilated to drive the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) using a newly adopted Lattice Kriging method (Wu & Lu, 2022, https://doi.org/10.1029/2021SW002880; Wu et al., 2022, https://doi.org/10.1029/2022SW003146). Compared to the default run, the TIEGCM simulation with assimilation captures: (a) secondary E‐region electron density peak due to aurora intensification; (b) strongly elevated ion temperatures (up to ∼3000 K) accompanied by a strong northward electric field (∼80 mV/m) and associated ion frictional heating; (c) elevation of electron temperatures; and (d) substantially enhanced neutral vertical winds (order of 50 m/s). Root‐mean‐square errors decrease by 30%–50%. The strong neutral upwelling is caused by large Joule heating down to ∼120 km resulting from enhanced aurora and electric field. Data assimilation increases the height‐integrated Joule heating at Poker Flat to a level of 50–100 mW/m2 while globally, its maximum value is comparable with the default run: the location of energy deposition becomes guided by data. Traveling atmospheric disturbances in the assimilation run show stronger magnitudes and larger extension leading to an increase of vertical wind variability by a factor of ∼1.5–3. Our work demonstrates that data assimilation of model drivers helps produce realistic storm‐time I‐T responses, which show richer dynamic range, scales, and variability than what has been simulated before.

Investigation of Interhemispheric Asymmetry of the Thermospheric Composition Observed by GOLD during the First Strong Geomagnetic Storm in Solar-Cycle 25, 1: IMF By Effects

Investigation of Interhemispheric Asymmetry of the Thermospheric Composition Observed by GOLD during the First Strong Geomagnetic Storm in Solar-Cycle 25, 1: IMF By Effects

The Solar Event of 14\u2009\u2013\u200915 July 2012 and Its Geoeffectiveness

During Solar Cycle 24, which started at the end of 2008, the Sun was calm, and there were not many spectacular geoeffective events. In this article, we analyze the geomagnetic storm that happened on 15 July 2012 during the 602nd anniversary of the Polish Battle of Grunwald, thus we propose this event to be called the “Battle of Grunwald Day Storm”. According to NOAA scale, it was a G3 geomagnetic storm with a southward component of the heliospheric magnetic field, Bz, falling to −20 nT, minimum Dst index of −139 nT, AE index of 1368 nT, and Ap index of 132 nT. It was preceded by a solar flare class X1.4 on 12 July. This geomagnetic storm was associated with the fast halo coronal mass ejection at 16:48:05 UT on 12 July, first appearance in the Large Angle and Spectroscopic Coronagraph C2, with a plane-of-sky speed of 885 km s−1 and maximum of 1415 km s−1. This geomagnetic storm was classified as the fourth strongest geomagnetic storm of Solar Cycle 24. At that time, a significant growth in the failures of the Polish electric transmission lines was observed, which could have a solar origin.

English

During geomagnetic storms, the geomagnetic H component is depressed which is preceded by a sudden storm commencement (SSC) or not and this is categorized as sudden or gradual storms. Using the method of cross correlation analysis, we have studied the associations of geomagnetic H components at four low latitude stations at longitudinal separations of 145° - 215° with solar wind density and interplanetary magnetic field (IMF) B during the four most intense sudden and four most intense gradual geomagnetic storms in solar cycle 23. In addition to dawn-dusk responses, how the ionospheric and magnetospheric currents respond to these variations at low latitudes during geomagnetic storms will be determined. Results show that profiles of cross correlation coefficients against time lags were superposed and had peak associations at zero time lags during each event for both parameters. Also there was no dawn-dusk variation in the profiles which implies that the magnetosphere responds uniquely to sources of external origin during geomagnetic storms at low latitudes.. Key words: Geomagnetic storms, solar wind and interplanetary magnetic field (IMF) parameters, geomagnetic H components.

Distribution of solar energetic particles and magnetic field orientations related to strong geomagnetic storms in solar cycle 24

Based on hourly data of solar energetic particles (velocity and density), interplanetary magnetic field (IMF) Bz component, and derived IMF orientations, e.g. IMF cone angle and clock angle, we studied their relations within 155 intense geomagnetic storms (Dst index less than -100 nT) during years 2009 to 2016 of solar cycle 24. The importance of negative and southward Bz was confirmed. It is suggested that strong geomagnetic storm also depends on IMF orientation angles, especially perpendicular IMF Bz. However, strong storms is not correlated with fast proton speed, which is aligned with perpendicular or parallel IMF cone angle. In the future, we can use those derived equations for prediction of solar storm.

The Role of a Tiny Brightening in a Huge Geoeffective Solar Eruption Leading to the St. Patrick’s Day Storm

Abstract The largest magnetic storm in solar cycle 24 was caused by a fast coronal mass ejection (CME) that was related to a small C9.1 flare that occurred on 2015 March 15 in solar active region (AR) NOAA 12297. The purpose of this study is to understand the onset mechanism of the geoeffective huge solar eruption. We focused on the C2.4 flare that occurred prior to the C9.1 flare of the filament eruption. The magnetic field structure in the AR was complicated: there were several filaments, including the one that erupted and caused the CME. We hence carefully investigated the photospheric magnetic field, brightenings observed in the solar atmosphere, and the 3D coronal magnetic field extrapolated from nonlinear force-free field modeling, using data from Hinode and Solar Dynamics Observatory. We found three intriguing points. (1) There was a compact but noticeably highly twisted magnetic field structure that is represented by a small filament in the C2.4 flaring region, where a tiny precursor brightening (PB) was observed before the C2.4 flare. (2) The C2.4 flaring region is located in the vicinity of a foot point of the closed field that prohibits the filament from erupting. (3) The filament shows a sudden eruption after the C2.4 flare and the accompanying small filament eruption. From our analysis, we suggest that a small magnetic disturbance that was represented by the tiny PB at the time of the C2.4 flare is related to the trigger of the huge filament eruption.

Global and local Joule heating during substorms in St. Patrick\u2019s Day 2015 geomagnetic storm

The first super storm of solar cycle 24 occurred on “St. Patrick’s Day” (17 March 2015), with a minimum Dst level of − 223 nT. Five major substorms in this super storm were selected, with minimum values of local electrojet index (IL) ranging from − 1662 to − 673 nT. The selected substorms are all in the 22:00 MLT–06:00 MLT sector of the auroral oval region showing associated Pi2s and negative bays in the H-component of magnetograms, derived from the IMAGE magnetometer longitudinal (Fennoscandia) chain. The solar wind energy input is estimated as time integral of Akasofu’s epsilon parameter, determined from the SuperMAG magnetometer. The local ionospheric Joule heating (local JH) rate, in the midnight or post-midnight sectors, is estimated using a modified form of Ahn’s empirical conversion. The Global ionospheric Joule heating rate in the northern hemisphere (global JH) is taken from OpenGGCM model. For the substorm in the main phase of the superstorm, the local JH consumes only 9% (8%, if the IL is replaced by AL index in the empirical conversion relation) of the global JH. However, 40–86% (39–48%, if the IL is replaced by AL index in the empirical conversion relation) of global JH is consumed as local JH for the remaining substorms.

The induced surface electric response in Europe to 2015 St. Patrick's Day geomagnetic storm

The largest geomagnetic storm in solar cycle 24 is investigated from the dual perspective of (1) solar source – solar wind – geomagnetic storm chain and (2) the hazardous induced response as shown by the surface electric field. The study is based on heliospheric magnetic field and solar wind data, on one hand, and on recorded 1-min geomagnetic data from the INTERMAGNET network of European geomagnetic observatories, on the other. The lateral distribution of the induced electric response for the European continent during the considered storm is shown, and the timing of the maximum induced horizontal geoelectric vector is discussed in terms of specific moments of the storm development.

Statistical comparison of the ICME's geoeffectiveness of different types and different solar phases from 1995 to 2014

AbstractThe geoeffectiveness of interplanetary coronal mass ejections (ICMEs) is an important issue in space weather research and forecasting. Based on the ICME catalog that we recently established and the Dst indices from the World Data Center, we study and compare the geoeffectiveness of ICMEs of different in situ signatures and different solar phases from 1995 to 2014. According to different in situ signatures, all ICMEs are divided into three types: isolated ICMEs (I‐ICMEs), multiple ICMEs (M‐ICMEs), and shock‐embedded ICMEs (S‐ICMEs), resulting in a total of 363 group events. The main findings of this work are as follows: (1) Fifty‐eight percent of ICMEs caused geomagnetic storms with Dstmin≤−30 nT. Further, large fraction (87%) of intense geomagnetic storms are caused by ICME groups and their sheath regions. (2) Numbers of ICME groups and the probabilities of ICME groups in causing geomagnetic storms varied in pace with the solar cycle. Meanwhile, the ICME groups and the probabilities of them in causing geomagnetic storms in Solar Cycle 24 are much lower than those in Solar Cycle 23. (3) The maximum value of the intensity of the magnetic field (B), south component of the magnetic field (Bs), and dawn‐dusk electric field vBs are well correlated with the intensity of the magnetic storms. (4) Shock‐embedded ICMEs have a high probability in causing geomagnetic storms, especially intense geomagnetic storms. (5) The compression of shock on the south component of magnetic field is an important factor to enhance the geoeffectiveness of S‐ICMEs structures.

Study of the effect of 17–18 March 2015 geomagnetic storm on the Indian longitudes using GPS and C/NOFS

AbstractThe largest geomagnetic storm in solar cycle 24 occurred during 17–18 March 2015 where the main phase of the storm commenced from 07:00 UT of 17 March 2015 and reached the Dst negative minimum at 22:00 UT. The present paper reports observations of total electron content (TEC), amplitude, and phase scintillations from different GPS stations of India during the storm of 17 March and highlights its effects on GPS. It also presents the global equatorial spread F (ESF) occurrence during the storm using total ion density drift measurements from Communication and Navigation Outage Forecast System (C/NOFS) satellite. TEC enhancements were noted from stations along 77°E meridian around 10:00 UT on 17 March compared to 16 and 18 March indicating positive storm effects arising out of equatorward neutral wind in the local morning to noon sector of the main phase. Intense scintillation observations from Calcutta were most extensive during 15:00–16:00 UT, 17 March, and the receiver recorded a longitude deviation of 5.2 m during this time. Cycle slips of the order of 8 s could be observed during periods of intense phase scintillations on the same night. Intense scintillation observation from Palampur is an exceptional phenomenon attributed to the dramatic enhancement of the electric field due to prompt penetrating (undershielded) electric leading to a very high upward ion velocity over the magnetic equator as recorded by C/NOFS. The total ion density measured globally by C/NOFS reveals two distinct longitude regions of ESF occurrence during the storm: (i) East Pacific sector and (ii) Indian longitude during the storm. The time and longitude of ESF occurrence could be predicted using the time of southward turning of interplanetary magnetic field Bz.

Positive and negative ionospheric responses to the March 2015 geomagnetic storm from BDS observations

The most intense geomagnetic storm in solar cycle 24 occurred on March 17, 2015, and the detailed ionospheric storm morphologies are difficultly obtained from traditional observations. In this paper, the Geostationary Earth Orbit (GEO) observations of BeiDou Navigation Satellite System (BDS) are for the first time used to investigate the ionospheric responses to the geomagnetic storm. Using BDS GEO and GIMs TEC series, negative and positive responses to the March 2015 storm are found at local and global scales. During the main phase, positive ionospheric storm is the main response to the geomagnetic storm, while in the recovery phase, negative phases are pronounced at all latitudes. Maximum amplitudes of negative and positive phases appear in the afternoon and post-dusk sectors during both main and recovery phases. Furthermore, dual-peak positive phases in main phase and repeated negative phase during the recovery are found from BDS GEO observations. The geomagnetic latitudes corresponding to the maximum disturbances during the main and recovery phases show large differences, but they are quasi-symmetrical between southern and northern hemispheres. No clear zonal propagation of traveling ionospheric disturbances is detected in the GNSS TEC disturbances at high and low latitudes. The thermospheric composition variations could be the dominant source of the observed ionospheric storm effect from GUVI $$\hbox {[O]/[N}_{2}]$$ ratio data as well as storm-time electric fields. Our study demonstrates that the BDS (especially the GEO) observations are an important data source to observe ionospheric responses to the geomagnetic storm.

Assessing ionospheric response during some strong storms in solar cycle 24 using various data sources

AbstractWe present an analysis of a regional ionospheric response during six strong storms (−200 nT ≤Dst≤−100 nT) that occurred in 2012 for the geographic latitudinal coverage of 10°S–40°S within a longitude sector of 10°E–40°E. Although these storms occurred during the same solar activity period and were all coronal mass ejection driven, their impacts and associated features on the ionosphere have been found different due to different contributing factors to their driving mechanisms. With the exception of one case, the rest of the storm periods were characterized by positive storm effects during the main and (or) recovery phases with varying physical mechanisms including low‐latitude electrodynamics, neutral composition changes, and traveling ionospheric disturbances (TIDs). The common result to all the analyzed strong storms was the presence of large‐scale TIDs during the storm main phases. Using total electron content data derived from the Global Navigational Satellite System (GNSS) observations and radio occultation (RO) electron density data on a regional scale, we have attempted to investigate meridional and vertical propagation of TIDs simultaneously during the strong storms. We have showed that it is possible to identify vertical motion of TIDs using RO data in cases when equatorward TIDs, as revealed by GNSS total electron content data, are present. RO results were compared to ionosonde data, and both data sources gave vertical velocities below 100 m/s of the associated TIDs.

Comparative ionospheric impacts and solar origins of nine strong geomagnetic storms in 2010–2015

AbstractFor nine of the strongest geomagnetic storms in solar cycle 24 we characterize, quantify, and compare the impacts on ionospheric total electron content (TEC) and the U.S. Wide Area Augmentation System (WAAS) with the heliospheric morphology and kinematics of the responsible coronal mass ejections (CMEs) and their solar source regions. Regional TEC responses to the events are similar in many respects, especially in the initial positive phase. For the subsequent negative phase, Dst is a better indicator than ap of the magnitude of the TEC decrease. The five events that arrive between 13:00 UT and 21:00 UT (local daytime in the U.S.) produce large WAAS degradations, and the four events that arrive outside this time of day produce lesser or no WAAS degradation. Our sample of geoeffective events includes CMEs with only modestly fast speeds, ones that only provided glancing impacts on Earth by their shock sheaths and ones not associated with any significant flare. While all of the CMEs traveled faster than the solar wind, they nevertheless have a wide range of velocities and produced a range of Bz values; neither speed nor Bz correlates significantly with ionospheric impact. Comparison with the locations of surface activity leads to estimates of deflection for the CMEs, with the average deflection being 19°. At least a few events may have missed Earth entirely in the absence of coronal deflection.

Estimation of interplanetary electric field conditions for historical geomagnetic storms

AbstractGround magnetic measurements provide a unique database in understanding space weather. The continuous geomagnetic records from Colaba‐Alibag observatories in India contain historically longest and continuous observations from 1847 to present date. Some of the super intense geomagnetic storms that occurred prior to 1900 have been revisited and investigated in order to understand the probable interplanetary conditions associated with intense storms. Following Burton et al. (1975), an empirical relationship is derived for estimation of interplanetary electric field (IEFy) from the variations of Dst index and ΔH at Colaba‐Alibag observatories. The estimated IEFy values using Dst and ΔHABG variations agree well with the observed IEFy, calculated using Advanced Composition Explorer (ACE) satellite observations for intense geomagnetic storms in solar cycle 23. This study will provide the uniqueness of each event and provide important insights into possible interplanetary conditions for intense geomagnetic storms and probable frequency of their occurrence.

Solar and interplanetary precursors of geomagnetic storms in solar cycle 23

Estimating the magnetic storm effectiveness of solar and associated interplanetary phenomena is of practical importance for space weather modelling and prediction. This article presents results of a qualitative and quantitative analysis of the probable causes of geomagnetic storms during the 11-year period of solar cycle 23: 1996–2006. Potential solar causes of 229 magnetic storms (Dst⩽−50nT) were investigated with a particular focus on halo coronal mass ejections (CMEs). A 5-day time window prior to the storm onset was considered to track backward the Sun’s eruptions of halo CMEs using the SOHO/LASCO CMEs catalogue list. Solar and interplanetary (IP) properties associated with halo CMEs were investigated and correlated to the resulting geomagnetic storms (GMS). In addition, a comparative analysis between full and partial halo CME-driven storms is established. The results obtained show that about 83% of intense storms (Dst⩽−100nT) were associated with halo CMEs. For moderate storms (−100nT<Dst⩽−50nT), only 54% had halo CME background, while the remaining 46% were assumed to be associated with corotating interaction regions (CIRs) or undetected frontside CMEs. It was observed in this study that intense storms were mostly associated with full halo CMEs, while partial halo CMEs were generally followed by moderate storms. This analysis indicates that up to 86% of intense storms were associated with interplanetary coronal mass ejections (ICMEs) at 1AU, as compared to moderate storms with only 44% of ICME association. Many other quantitative results are presented in this paper, providing an estimate of solar and IP precursor properties of GMS within an average 11-year solar activity cycle. The results of this study constitute a key step towards improving space weather modelling and prediction.

Modeling the superstorm in November 2003

The superstorm on 20.21 November 2003 was the largest geomagnetic storm in solar cycle 23 as measured by Dst, which attained a minimum value of .422 nT. We have simulated this storm to understand how particles originating from the solar wind and ionosphere get access to the magnetosphere and how the subsequent transport and energization processes contribute to the buildup of the ring current. The global electromagnetic configuration and the solar wind H+ distribution are specified by the Lyon-Fedder-Mobarry (LFM) magnetohydrodynamics model. The outflow of H+ and O+ ions from the ionosphere are also considered. Their trajectories in the magnetosphere are followed by a test-particle code. The particle distributions at the inner plasma sheet established by the LFM model and test-particle calculations are then used as boundary conditions for a ring current model. Our simulations reproduce the rapid decrease of Dst during the storm main phase and the fast initial phase of recovery. Shielding in the inner magnetosphere is established at early main phase. This shielding field lasts several hours and then breaks down at late main phase. At the peak of the storm, strong penetration of ions earthward to L shell of 1.5 is revealed in the simulation. It is surprising that O+ is significant but not the dominant species in the ring current in our calculation for this major storm. It is very likely that substorm effects are not well represented in the models and O+ energization is underestimated. Ring current simulation with O+ energy density at the boundary set comparable to Geotail observations produces excellent agreement with the observed symH. As expected in superstorms, ring current O+ is the dominant species over H+ during the main to mid-recovery phase of the storm.

Response of the midlatitude ionosphere to extreme geomagnetic storms of the 23rd solar cycle

The ionospheric response in the Irkutsk region (52.3° N, 104.3° E) to the extreme geomagnetic storms of solar cycle 23 was studied based on the data of the Irkutsk incoherent scatter radar (ISR) and DPS-4 vertical sounding digital ionosonde. The deviations of parameters from the undisturbed level, i.e., from the monthly medians or the values obtained on a quiet day, were considered as an ionospheric response. Values of the electron concentration maximum (NmF2) and electron temperature (Te) at a height of 350 km were chosen as parameters. The ionospheric response is interpreted in the scope of the concept of a thermospheric storm and penetration of the magnetospheric electric field.

The Solar and Interplanetary Causes of Space Storms in Solar Cycle 23

This paper presents a brief overview on the results of a joint EU-INTAS-ESA project, which is focused on the investigation of the interplanetary and solar causes of geomagnetic storms in solar cycle 23. Based on the in situ data of the solar wind plasma and magnetic field parameters measured by the Wind and ACE (Advanced Composition Explorer) spacecraft, in joint analysis with the unprecedented set of remote sensing observations provided by the SOHO (Solar and Heliospheric Observatory) satellite since its launch in December 1995, the main statistical results from the detailed investigation of geomagnetic disturbed days with Ap>20 are presented here.