Coronal shocks associated with CMEs and flares and their space weather consequences (original) (raw)
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Solar flares with and without SOHO/LASCO coronal mass ejections and type II shocks
Advances in Space Research, 2006
An analysis is presented of a set of radio rich solar SXR flares, i.e. accompanied by type IV or II metric radio bursts, associated with Coronal Mass Ejections and MHD shocks, recorded as type II events, in the period 1998-2000. The relative size, impulsiveness and energetics of these events are investigated. We find that, on the average, the flares with type II bursts and CMEs are larger, more impulsive and energetic from the flares with type II but without CMEs. The latter are more energetic than flares associated with relatively slow CMEs accompanied by type IV continua but not type II shocks. Although a simple classification may not be readily determined the results imply that associated energetic events originate, more often than not, from sources with characteristics fairly well correlated.
Solar flares associated coronal mass ejections in case of type II radio bursts
Astrophysics and Space Science, 2016
In this paper, we have selected 114 flare-CME events accompanied with Deca-hectometric (DH) type II radio burst chosen from 1996 to 2008 (i.e., solar cycle 23). Statistical analyses are performed to examine the relationship of flare-CME events accompanied with DH type II radio burst with Interplanetary Magnetic field (IMF), Geomagnetic storms (GSs) and Cosmic Ray Intensity (CRI). The collected sample events are divided into two groups. In the first group, we considered 43 events which lie under the CME span and the second group consists of 71 events which are outside the CME span. Our analysis indicates that flare-CME accompanied with DH type II radio burst is inconsistent with CSHKP flare-CME model. We apply the Chree analysis by the superposed epoch method to both set of data to find the geo-effectiveness. We observed different fluctuations in IMF for arising and decay phase of solar cycle in both the cases. Maximum decrease in Dst during arising and decay phase of solar cycle is different for both the cases. It is noted that when flare lie outside the CME span CRI shows comparatively more variation than the flare lie under the CME span. Furthermore, we found that flare lying under the CME span is more geo effective than the flare outside of CME span. We noticed that the time leg between IMF Peak value and GSs, IMF and CRI is on average one day for both the cases. Also, the time leg between CRI and GSs is on average 0 to 1 day for both the cases. In case flare lie under the CME span we observed high correlation (0.64) between CRI and Dst whereas when flare lie outside the CME span a weak correlation (0.47) exists. Thus, flare position with respect to CME span play a key role for geo-effectiveness of CME.
The energetic relationship among geoeffective solar flares, associated CMEs and SEPs
Research in Astronomy and Astrophysics, 2013
Major solar eruptions (flares, coronal mass ejections (CMEs) and solar energetic particles (SEPs)) strongly influence geospace and space weather. Currently, the mechanism of their influence on space weather is not well understood and requires a detailed study of the energetic relationship among these eruptive phenomena. From this perspective, we investigate 30 flares (observed by RHESSI), followed by weak to strong geomagnetic storms. Spectral analysis of these flares suggests a new power-law relationship (r ∼ 0.79) between the hard X-ray (HXR) spectral index (before flarepeak) and linear speed of the associated CME observed by LASCO/SOHO. For 12 flares which were followed by SEP enhancement near Earth, HXR and SEP spectral analysis reveals a new scaling law (r ∼ 0.9) between the hardest X-ray flare spectrum and the hardest SEP spectrum. Furthermore, a strong correlation is obtained between the linear speed of the CME and the hardest spectrum of the corresponding SEP event (r ∼ 0.96). We propose that the potentially geoeffective flare and associated CME and SEP are well-connected through a possible feedback mechanism, and should be regarded within the framework of a solar eruption. Owing to their space weather effects, these new results will help improve our current understanding of the Sun-Earth relationship, which is a major goal of research programs in heliophysics.
Solar origins of intense geomagnetic storms in 2002 as seen by the CORONAS-F satellite
Advances in Space Research, 2005
We analyze solar origins of intense geomagnetic perturbations recorded during 2002. All of them were related to coronal mass ejections (CMEs). The initiation of CMEs was documented using the SPIRIT instrument (SPectrohelIographic Soft X-Ray Imaging Telescope) onboard the CORONAS-F satellite. Monochromatic full Sun images taken in the Mg XII doublet at 8.418 and 8.423 Å showed the appearance of free energy release sites at altitudes up to 0.4 solar radii. CMEs were initiated at these sites and propagated in interplanetary space under appropriate local conditions including the geometry of the magnetic fields.
American Based Research Journal, 2019
Coronal Mass Ejections (CMEs) are the drastic solar events in which huge amount of solar plasma materials are ejected into the heliosphere from the sun and are mainly responsible to generate large disturbances in solar wind plasma parameters and geomagnetic storms in the geomagnetic field. We have studied geomagnetic storms, (Dst ≤-90nT) observed during the period of 1997-2012 with Coronal Mass Ejections and disturbances in solar wind plasma parameters (velocity). We have inferred that most of the geomagnetic storms are associated with halo and partial-halo Coronal Mass Ejections (CMEs). The association rate of halo and partial halo coronal mass ejections are found 75 % and 25 % respectively. Further, we have concluded that geomagnetic storms are closely associated with the disturbances in solar wind plasma parameters. We have determined a positive correlation between the magnitudes of geomagnetic storms and speed of CMEs with correlation coefficient 0.26. Further Positive co-relation has been found between the speed of CMEs and peak velocity of jump in solar wind plasma velocity. Statistically calculated co-relation coefficient is 0.31 between these two events. Again there is a Positive co-relation has been found between the speed of CMEs and magnitude of jump in solar wind plasma velocity with correlation coefficient 0.20. Furthermore, we observe the positive correlation between the magnitude of geomagnetic storms and the peak value of JSWV events and statistically calculated co-relation coefficient is 0.42 between these two events. We have concluded that geomagnetic storms are mainly caused by Coronal Mass Ejections and disturbances in solar wind plasma parameters that they generate.
Solar Flares and Geomagnetic Storms (Data collection and analysis
-The causality relation between solar flares and the coronal mass ejections has been thought as that as the coronal mass ejections result from strong solar flares, as far as geomagnetic storms controlled by coronal mass ejections. This study focused on such relation, through statistical analysis by calculating the correlation coefficient between solar flares and (A) index data for (21) years, namely (1996-2016).The correlation coefficient calculated for different intervals. The results emphasized the common known fact for long time period, while zooming on shorter intervals revealed that not every strong solar flare creates a coronal mass ejection, and the coronal mass ejections are not the only factor that affects the geomagnetic field.
2019
Solar energetic particles (SEPs) and geomagnetic storms related to coronal mass ejections (CMEs) are a major research topic in solar-terrestrial and geospace physics. Solar energetic particles and coronal mass ejections can impact the Earth’s ionospheremagnetosphere-atmosphere system and lead to various adverse effects on space-born and ground-based technologies. This doctoral dissertation investigates the dependence of the properties of SEP events and geomagnetic storms on the parameters characterizing the CMEs and solar phenomena temporally related to the CMEs, such as solar flares and radio bursts. We have carried out a statistical study of the properties of geomagnetic storms and SEP events associated with full-halo CMEs originating from close to the solar disk centre. We found that 50 % of all the selected CMEs were geoeffective and 39 % of these CMEs were associated with SEP events. We also investigated the dependence of the occurrence rate and strength of geomagnetic storms o...
The solar flare and Coronal Mass Ejections (CMEs) are well known as one of the most massive eruptions which potentially create major disturbances in the interplanetary medium and initiate severe magnetic storms when they collide with the Earth‟s magnetosphere. However, how far the solar flare can contribute to the formation of the CMEs is still not easy to be understood. These phenomena are associated with II and III burst it also divided by sub-type of burst depending on the physical characteristics and different mechanisms. In this work, we used a Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy in Transportable Observatories (CALLISTO) system. The aim of the present study is to reveal dynamical properties of solar burst type II and III due to several mechanisms. Most of the cases of both solar radio bursts can be found in the range less that 400 MHz. Based on solar flare monitoring within 24 hours, the CMEs that has the potential to explode will dominantly be a class of M1 solar flare. Overall, the tendencies of SRBT III burst form the solar radio burst type III at 187 MHz to 449 MHz. Based on solar observations, it is evident that the explosive, short time-scale energy release during flares and the long term, gradual energy release expressed by CMEs can be reasonably understood only if both processes are taken as common and probably not independent signatures of a destabilization of pre-existing coronal magnetic field structures. The configurations of several active regions can be sourced regions of CMEs formation. The study of the formation, acceleration and propagation of CMEs requires advanced and powerful observational tools in different spectral ranges as many „stages‟ as possible between the photosphere of the Sun and magnetosphere of the Sun and magnetosphere of the Earth. In conclusion, this range is a current regime of solar radio bursts during CMEs events.
Solar and interplanetary sources of major geomagnetic storms during 1996–2002
Journal of Geophysical Research, 2004
1] During the 7-year period of the current solar cycle, 64 geoeffective coronal mass ejections (CMEs) were found to produce major geomagnetic storms (D ST < À100 nT) at the Earth. In this paper we examine solar and interplanetary properties of these geoeffective coronal mass ejections (CMEs). The observations reveal that full-halo CMEs are potential sources of intense geomagnetic activity at the Earth. However, not all fullhalo CMEs give rise to major geomagnetic storms, which complicates the task of space weather forecasting. We examine solar origins of the geoeffective CMEs and their interplanetary effects, namely, solar wind speed, interplanetary shocks, and the southward component of the interplanetary magnetic field, in order to investigate the relationship between the solar and interplanetary parameters. In particular, the present study aims at ascertaining solar parameters that govern important interplanetary parameters responsible for producing major geomagnetic storms. Our investigation shows that fast full-halo CMEs associated with strong flares and originating from a favorable location, i.e., close to the central meridian and low and middle latitudes, are the most potential candidates for producing strong ram pressure at the Earth's magnetosphere and hence intense geomagnetic storms. The results also show that the intensity of geomagnetic storms depends most strongly on the southward component of the interplanetary magnetic field, followed by the initial speed of the CME and the ram pressure.
Space storm measurements of the July 2005 solar extreme events from the low corona to the Earth
The Athens Neutron Monitor Data Processing (ANMODAP) Center recorded an unusual Forbush decrease with a sharp enhancement of cosmic ray intensity right after the main phase of the Forbush decrease on 16 July 2005, followed by a second decrease within less than 12 h. This exceptional event is neither a ground level enhancement nor a geomagnetic effect in cosmic rays. It rather appears as the effect of a special structure of interplanetary disturbances originating from a group of coronal mass ejections (CMEs) in the 13-14 July 2005 period. The initiation of the CMEs was accompanied by type IV radio bursts and intense solar flares (SFs) on the west solar limb (AR 786); this group of energetic phenomena appears under the label of Solar Extreme Events of July 2005. We study the characteristics of these events using combined data from Earth (the ARTEMIS IV radioheliograph, the Athens Neutron Monitor (ANMODAP)), space (WIND/WAVES) and data archives. We propose an interpretation of the unusual Forbush profile in terms of a magnetic structure and a succession of interplanetary shocks interacting with the magnetosphere.