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1.
Coronal mass ejections (CMEs) are considered as one of the driving sources of space weather. They are usually associated with many physical phenomena, e.g. flares, coronal dimmings, and sigmoids. To detect these phenomena, traditional supervised-learning methods assumed that at most one event occurred in a CME; therefore each CME instance is associated with a single label and the phenomenon is processed in isolation. This simplifying assumption does not fit well, as CMEs might have multiple events simultaneously. We propose to detect multiple CME-associated events by multi-label learning methods. With the data available from the Atmospheric Imaging Assembly (AIA) and the Large Angle and Spectrometric Coronagraph (LASCO), texture features representing the events are extracted from all of the associated and not-associated CMEs and converted into feature vectors for multi-label learning use. Then a function is learned to predict the proper label sets for CMEs, such that eight events, i.e. coronal dimming, coronal hole, coronal jet, coronal wave, filament, filament eruption, flare, and sigmoid, are detected explicitly. To test the proposed detection algorithm, we adopt the four-fold cross-validation strategy on a set of 551 labeled CMEs from AIA. Experimental results demonstrate the good performance of the multi-label classification methods in terms of test error. 相似文献
2.
We present a study of the origin of coronal mass ejections (CMEs) that were not accompanied by obvious low coronal signatures (LCSs) and yet were responsible for appreciable disturbances at 1 AU. These CMEs characteristically start slowly. In several examples, extreme ultraviolet (EUV) images taken by the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory reveal coronal dimming and a post-eruption arcade when we make difference images with long enough temporal separations, which are commensurate with the slow initial development of the CME. Data from the EUV imager and COR coronagraphs of the Sun Earth Connection Coronal and Heliospheric Investigation onboard the Solar Terrestrial Relations Observatory, which provide limb views of Earth-bound CMEs, greatly help us limit the time interval in which the CME forms and undergoes initial acceleration. For other CMEs, we find similar dimming, although only with lower confidence as to its link to the CME. It is noted that even these unclear events result in unambiguous flux rope signatures in in situ data at 1 AU. There is a tendency that the CME source regions are located near coronal holes or open field regions. This may have implications for both the initiation of the stealthy CME in the corona and its outcome in the heliosphere. 相似文献
3.
We present detailed observations of the formations of four distinct coronal dimmings during a flare of 17 September 2002,
which was followed by an eruption of a huge coronal loop system, and then an over-and-out partial halo coronal mass ejection
(CME), with the same direction as the loop system eruption but laterally far offset from the flare site. Among the four dimmings,
two compact ones were symmetrically located in the opposite polarity regions immediately adjacent to the highly sheared magnetic
polarity inversion line in the flare region, and hence were probably composed of bipolar double dimmings due to a flux-rope
eruption and represented its evacuated footpoints. However, another nearby compact dimming and a remote diffuse one were formed
in the opposite polarity footpoint regions of the eruptive loop system, and thus probably consisted of a pair of dimmings
magnetically linked by the erupting loop system and also indicated its evacuated footpoints. The loop system might have played
a role in guiding the erupting flare field and producing the over-and-out CME, but its eruption might simply have been pushed
out by the erupting flare field, because there was no reconnection signature between them. From comparison with a derived
potential-field source-surface (PFSS) magnetic configuration, our observations consistently suggest that the dimmings were
formed in pairs and originated from the eruptions of the two different magnetic systems. We thus define them as “quadrupolar
dimmings.” 相似文献
4.
We investigate the early phase of the 13 February 2009 coronal mass ejection (CME). Observations with the twin STEREO spacecraft
in quadrature allow us to compare for the first time in one and the same event the temporal evolution of coronal EUV dimmings,
observed simultaneously on-disk and above-the-limb. We find that these dimmings are synchronized and appear during the impulsive
acceleration phase of the CME, with the highest EUV intensity drop occurring a few minutes after the maximum CME acceleration.
During the propagation phase two confined, bipolar dimming regions, appearing near the footpoints of a pre-flare sigmoid structure,
show an apparent migration away from the site of the CME-associated flare. Additionally, they rotate around the ‘center’ of
the flare site, i.e., the configuration of the dimmings exhibits the same ‘sheared-to-potential’ evolution as the postflare loops. We conclude
that the motion pattern of the twin dimmings reflects not only the eruption of the flux rope, but also the ensuing stretching
of the overlying arcade. Finally, we find that: i) the global-scale dimmings, expanding from the source region of the eruption, propagate with a speed similar to that of the
leaving CME front; ii) the mass loss occurs mainly during the period of strongest CME acceleration. Two hours after the eruption Hinode/EIS observations show no substantial plasma outflow, originating from the ‘open’ field twin dimming regions. 相似文献
5.
We report on the occurrence of Hα dimming associated with a sigmoid eruption in a quiet-sun region on 14 August 2001. The
coronal sigmoid in soft X-ray images from the Yohkoh Soft X-ray Telescope was located over an Hα filament channel. Its eruption was accompanied by a flare of GOES X-ray class
C2.3 and possibly associated with a halo coronal mass ejection (CME) observed with the Large Angle and Spectroscopic Coronagraphs (LASCO) on board the Solar and Heliospheric Observatory (SOHO). During the eruption, coronal bipolar double dimming took place at the regions with opposite magnetic polarities around
the two sigmoid ends, but the underlying chromospheric channel did not show observable changes corresponding to the coronal
eruption. Different from the erupting coronal sigmoid itself, however, the coronal dimming had a detectable chromosphere counterpart,
i.e., Hα dimming. By regarding the sigmoid as a coronal sign for a flux rope, these observations are explained in the framework
of the flux rope model of CMEs. The flux rope is possibly deeply rooted in the chromosphere, and the coronal and Hα dimming
regions mark its evacuated feet, through which the material is possibly fed to the halo CME. 相似文献
6.
Manuela Temmer Julia K. Thalmann Karin Dissauer Astrid M. Veronig Johannes Tschernitz Jürgen Hinterreiter Luciano Rodriguez 《Solar physics》2017,292(7):93
We analyze the well-observed flare and coronal mass ejection (CME) from 1 October 2011 (SOL2011-10-01T09:18) covering the complete chain of effects – from Sun to Earth – to better understand the dynamic evolution of the CME and its embedded magnetic field. We study in detail the solar surface and atmosphere associated with the flare and CME using the Solar Dynamics Observatory (SDO) and ground-based instruments. We also track the CME signature off-limb with combined extreme ultraviolet (EUV) and white-light data from the Solar Terrestrial Relations Observatory (STEREO). By applying the graduated cylindrical shell (GCS) reconstruction method and total mass to stereoscopic STEREO-SOHO (Solar and Heliospheric Observatory) coronagraph data, we track the temporal and spatial evolution of the CME in the interplanetary space and derive its geometry and 3D mass. We combine the GCS and Lundquist model results to derive the axial flux and helicity of the magnetic cloud (MC) from in situ measurements from Wind. This is compared to nonlinear force-free (NLFF) model results, as well as to the reconnected magnetic flux derived from the flare ribbons (flare reconnection flux) and the magnetic flux encompassed by the associated dimming (dimming flux). We find that magnetic reconnection processes were already ongoing before the start of the impulsive flare phase, adding magnetic flux to the flux rope before its final eruption. The dimming flux increases by more than 25% after the end of the flare, indicating that magnetic flux is still added to the flux rope after eruption. Hence, the derived flare reconnection flux is most probably a lower limit for estimating the magnetic flux within the flux rope. We find that the magnetic helicity and axial magnetic flux are lower in the interplanetary space by ～?50% and 75%, respectively, possibly indicating an erosion process. A CME mass increase of 10% is observed over a range of \({\sim}\,4\,\mbox{--}\,20~\mathrm{R}_{\odot }\). The temporal evolution of the CME-associated core-dimming regions supports the scenario that fast outflows might supply additional mass to the rear part of the CME. 相似文献
7.
The volume of data anticipated from the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) highlights the necessity for the development of automatic-detection methods for various types of solar activity. Initially recognized in the 1970s, it is now well established that coronal dimmings are closely associated with coronal mass ejections (CMEs), and they are particularly noted as a reliable indicator of front-side (halo) CMEs, which can be difficult to detect in white-light coronagraph data. Existing work clearly demonstrates that several properties derived from the analysis of coronal dimmings can give useful information about the associated CME. The development and implementation of an automated coronal-dimming region detection and extraction algorithm removes visual observer bias, however unintentional, from the determination of physical quantities such as spatial location, area, and volume. This allows for reproducible, quantifiable results to be mined from very large data sets. The information derived may facilitate more reliable early space-weather detection, as well as offering the potential for conducting large-sample studies focused on determining the geo-effectiveness of CMEs, coupled with analysis of their associated coronal dimming signatures. In this paper we present examples of both simple and complex dimming events extracted using our algorithm, which will be run as a module for the SDO/Computer Vision Centre. Contrasting and well-studied events at both the minimum and maximum of solar cycle 23 are identified in Solar and Heliospheric Observatory/Extreme ultra-violet Imaging Telescope (SOHO/EIT) data. A more recent example extracted from Solar and Terrestrial Relations Observatory/Extreme Ultra-Violet Imager (STEREO/EUVI) data is also presented, demonstrating the potential for the anticipated application to SDO/AIA data. The detection part of our algorithm is based largely on the principle of operation of the NEMO software, namely the detection of significant variation in the statistics of the EUV image pixels (Podladchikova and Berghmans in Solar Phys. 228, 265?–?284, 2005). As well as running on historic data sets, the presented algorithm is capable of detecting and extracting coronal dimmings in near real-time. 相似文献
8.
We have analyzed dimmings, i.e., regions of temporarily reduced brightness, and manifestations of a coronal wave in the famous event of 14 July 2000 using images produced with the EUV telescope SOHO/EIT. Our analysis was inspired by a paper by Andrews (2001, Solar Phys. 204, 181 (Paper I)), in which this event was studied using running-difference EIT images at 195 Å formed by subtraction of a previous image from each current one. Such images emphasize changes of the brightness, location, and configuration of observed structures occurring during the 12-min interval between two subsequent heliograms. However, they distort the picture of large-scale disturbances caused by a CME, particularly, dimmings. A real picture of dimmings can be obtained from fixed-base difference ‘de-rotated’ images. The latter are formed in two stages: first, the solar rotation is compensated using three-dimensional rotation of all images (‘de-rotation’) to the time of a pre-event heliogram, here 10:00 UT, and then the base heliogram is subtracted from all others. We show real dimmings to be essentially different from those described by Andrews (Paper I). The restructuring of large-scale magnetic fields in the corona in connection with the CME was accompanied by the appearance and growth of two large dimmings. One of them was located along the central meridian, southward of the eruption center, at the place of the pre-eruption arcade. Another dimming occupied the space between the flare region and a remote western active region. Several smaller dimmings were observed virtually over the whole solar disk, especially, within the northwest quadrant. We have also revealed a propagating disturbance with properties of a coronal wave in the northern polar sector, where no dimmings were observed. This fact is discussed in the context of probable association between dimmings and coronal waves. Having suppressed the ‘snowstorm’ produced in the EIT images by energetic particles, we have considered dimming manifestations in all four EIT pass bands of 171, 195, 284, and 304 Å as well as the light curves of the main dimmings including several later images at 195 Å. Our analysis shows that the major cause of the dimmings was density depletion that reached up to 30% in this event. The picture of dimmings implies that the CME in the Bastille Day event was an octopus-like bundle of some magnetic ropes, with the ‘arms’ being connected to several active regions disposed over almost the whole visible solar surface. 相似文献
9.
STEREO/EUVI observed 185 flare events (detected above the GOES class C1 level or at >?25 keV with RHESSI) during the first two years of the mission (December 2006?–?November 2008), while coronal mass ejections (CMEs) were reported in about a third of these events. We compile a comprehensive catalog of these EUVI-observed events, containing the peak fluxes in soft X rays, hard X rays, and EUV, as well as a classification and statistics of prominent EUV features: 79% show impulsive EUV emission (coincident with hard X rays), 73% show delayed EUV emission from postflare loops and arcades, 24% represent occulted flares, 17% exhibit EUV dimming, 5% show loop oscillations or propagating waves, and at least 3% show erupting filaments. We analyze an example of each EUV feature by stereoscopic modeling of its 3D geometry. We find that EUV emission can be dominated by impulsive emission from a heated, highly sheared, noneruptive filament, in addition to the more common impulsive EUV emission from flare ribbons or the delayed postflare EUV emission that results from cooling of the soft-X-ray-emitting flare loops. Occulted flares allow us to determine CME-related coronal dimming uncontaminated from flare-related EUV emission. From modeling the time evolution of EUV dimming we can accurately quantify the initial expansion of CMEs and determine their masses. Further, we find evidence that coronal loop oscillations are excited by the rapid initial expansion of CMEs. These examples demonstrate that stereoscopic EUV data provide powerful new methods to model the 3D aspects in the hydrodynamics of flares and kinematics of CMEs. 相似文献
10.
H. Xie O. C. St. Cyr N. Gopalswamy S. Yashiro J. Krall M. Kramar J. Davila 《Solar physics》2009,259(1-2):143-161
We have conducted a statistical study 27 coronal mass ejections (CMEs) from January 2007 – June 2008, using the stereoscopic views of STEREO SECCHI A and B combined with SOHO LASCO observations. A flux-rope model, in conjunction with 3D triangulations, has been used to reconstruct the 3D structures and determine the actual speeds of CMEs. The origin and the dynamic evolution of the CMEs are investigated using COR1, COR2 and EUVI images. We have identified four types of solar surface activities associated with CMEs: i) total eruptive prominence (totEP), ii) partially eruptive prominence (PEP), iii) X-ray flare, and iv) X-type magnetic structure (X-line). Among the 27 CMEs, 18.5% (5 of 27) are associated with totEPs, 29.6% (8 of 27) are associated with PEPs, 26% (7 of 27) are flare related, and 26% (7 of 27) are associated with X-line structures, and 43% (3 of 7) are associated with both X-line structures and PEPs. Three (11%) could not be associated with any detectable activity. The mean actual speeds for totEP-CMEs, PEP-CMEs, flare-CMEs, and X-line-CMEs are 404 km?s?1,247 km?s?1,909 km?s?1, and 276 km?s?1, respectively; the average mean values of edge-on and broadside widths for the 27 CMEs are 52 and 85 degrees, respectively. We found that slow CMEs (V≤400 km?s?1) tend to deflect towards and propagate along the streamer belts due to the deflections by the strong polar magnetic fields of corona holes, while some faster CMEs show opposite deflections away from the streamer belts. 相似文献
11.
We present the first evidence for occurrences of magnetic interactions between a jet, a filament and coronal loops during a complex event, in which two flares sequen-tially occurred at different positions of the same active region and were closely associated with two successive coronal mass ejections (CMEs), respectively. The coronal loops were located outside but nearby the filament channel before the flares. The jet, originating from the first flare during its rise phase, not only hit the filament body but also met one of the ends of the loops. The filament then underwent an inclined eruption followed by the second flare and met the same loop end once more. Both the jet and the filament erup- tion were accompanied by the development of loop disturbances and the appearances of brightenings around the meeting site. In particular, the erupting filament showed clear manifestations of interactions with the loops. After a short holdup, only its portion passed through this site, while the other portion remained at the same place. Following the fila-ment eruption and the loop disappearance, four dimmings were formed and located near their four ends. This is a situation that we define as "quadrupolar dimmings." It appears that the two flares consisted of a sympathetic pair physically linked by the interaction between the jet and the filament, and their sympathy indicated that of the two CMEs.Moreover, it is very likely that the two sympathetic CMEs were simultaneously associ-ated with the disappearing loops and the quadrupole dimmings. 相似文献
12.
C. H. Mandrini M. S. Nakwacki G. Attrill L. van Driel-Gesztelyi P. Démoulin S. Dasso H. Elliott 《Solar physics》2007,244(1-2):25-43
Coronal dimmings are often present on both sides of erupting magnetic configurations. It has been suggested that dimmings
mark the location of the footpoints of ejected flux ropes and, thus, their magnetic flux can be used as a proxy for the flux
involved in the ejection. If so, this quantity can be compared to the flux in the associated interplanetary magnetic cloud
to find clues about the origin of the ejected flux rope. In the context of this physical interpretation, we analyze the event,
flare, and coronal mass ejection (CME) that occurred in active region 10486 on 28 October 2003. The CME on this day is associated
with large-scale dimmings, located on either side of the main flaring region. We combine SOHO/Extreme Ultraviolet Imaging
Telescope data and Michelson Doppler Imager magnetic maps to identify and measure the flux in the dimming regions. We model
the associated cloud and compute its magnetic flux using in situ observations from the Magnetometer Instrument and the Solar Wind Electron Proton Alpha Monitor aboard the Advance Composition Explorer. We find that the magnetic fluxes of the dimmings and magnetic cloud are incompatible, in contrast to what has been found
in previous studies. We conclude that, in certain cases, especially in large-scale events and eruptions that occur in regions
that are not isolated from other flux concentrations, the interpretation of dimmings requires a deeper analysis of the global
magnetic configuration, since at least a fraction of the dimmed regions is formed by reconnection between the erupting field
and the surrounding magnetic structures. 相似文献
13.
Studies of the onset of Earth-directed coronal mass ejections (CMEs) rely on solar disk observations where CME structures
are difficult to disentangle because of the diversity and transient character of the phenomena involved. Dimmings and coronal
waves are among the best evidence of the large-scale reorganization of coronal magnetic fields associated with the onset of
CMEs. The physical mechanism behind EIT waves is still unclear: they are considered as MHD waves and/or as a consequence of
plasma compression on the extending border of a dimming. In this paper, we address the problem of automatically detecting
and analyzing EIT waves and dimmings in EUV images. This paper presents a “proof of principle” that automated detection of
EIT wave and dimmings is indeed possible. At the current stage of work, the method can unambiguously detect dimmings and EIT
waves when applied on a typical test-case event. Moreover, we propose a way to extract these events from the data, and determine
such parameters as life time, depth, area and volume of dimmings for future catalogs. For EIT waves we unambiguously define,
in near solar minimum conditions, the eruption center, the front of EIT wave and its propagation velocity. In addition, we
show that the presented methods yield new insights about the geometrical shape of dimmings and the connection with the EIT
wave front properties, and the apparent angular rotation of the EIT wave under study. 相似文献
14.
Coronal holes (CHs) are regions of open magnetic field lines in the solar corona and the source of the fast solar wind. Understanding the evolution of coronal holes is critical for solar magnetism as well as for accurate space weather forecasts. We study the extreme ultraviolet (EUV) synoptic maps at three wavelengths (195 Å/193 Å, 171 Å and 304 Å) measured by the Solar and Heliospheric Observatory/Extreme Ultraviolet Imaging Telescope (SOHO/EIT) and the Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) instruments. The two datasets are first homogenized by scaling the SDO/AIA data to the SOHO/EIT level by means of histogram equalization. We then develop a novel automated method to identify CHs from these homogenized maps by determining the intensity threshold of CH regions separately for each synoptic map. This is done by identifying the best location and size of an image segment, which optimally contains portions of coronal holes and the surrounding quiet Sun allowing us to detect the momentary intensity threshold. Our method is thus able to adjust itself to the changing scale size of coronal holes and to temporally varying intensities. To make full use of the information in the three wavelengths we construct a composite CH distribution, which is more robust than distributions based on one wavelength. Using the composite CH dataset we discuss the temporal evolution of CHs during the Solar Cycles 23 and 24. 相似文献
15.
Using in situ observations from the Advanced Composition Explorer (ACE), we have identified 70 Earth-affecting interplanetary coronal mass ejections (ICMEs) in Solar Cycle 24. Because of the unprecedented extent of heliospheric observations in Cycle 24 that has been achieved thanks to the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instruments onboard the Solar Terrestrial Relations Observatory (STEREO), we observe these events throughout the heliosphere from the Sun to the Earth, and we can relate these in situ signatures to remote sensing data. This allows us to completely track the event back to the source of the eruption in the low corona. We present a summary of the Earth-affecting CMEs in Solar Cycle 24 and a statistical study of the properties of these events including the source region. We examine the characteristics of CMEs that are more likely to be strongly geoeffective and examine the effect of the flare strength on in situ properties. We find that Earth-affecting CMEs in the first half of Cycle 24 are more likely to come from the northern hemisphere, but after April 2012, this reverses, and these events are more likely to originate in the southern hemisphere, following the observed magnetic asymmetry in the two hemispheres. We also find that as in past solar cycles, CMEs from the western hemisphere are more likely to reach Earth. We find that Cycle 24 lacks in events driving extreme geomagnetic storms compared to past solar cycles. 相似文献
16.
The Recovery of CME-Related Dimmings and the ICME’s Enduring Magnetic Connection to the Sun 总被引：1，自引：1，他引：0
G. D. R. Attrill L. van Driel-Gesztelyi P. Démoulin A. N. Zhukov K. Steed L. K. Harra C. H. Mandrini J. Linker 《Solar physics》2008,252(2):349-372
It is generally accepted that transient coronal holes (TCHs, dimmings) correspond to the magnetic footpoints of CMEs that
remain rooted in the Sun as the CME expands out into the interplanetary space. However, the observation that the average intensity
of the 12 May 1997 dimmings recover to their pre-eruption intensity in SOHO/EIT data within 48 hours, whilst suprathermal
unidirectional electron heat fluxes are observed at 1 AU in the related ICME more than 70 hours after the eruption, leads
us to question why and how the dimmings disappear whilst the magnetic connectivity is maintained. We also examine two other
CME-related dimming events: 13 May 2005 and 6 July 2006. We study the morphology of the dimmings and how they recover. We
find that, far from exhibiting a uniform intensity, dimmings observed in SOHO/EIT data have a deep central core and a more
shallow extended dimming area. The dimmings recover not only by shrinking of their outer boundaries but also by internal brightenings.
We quantitatively demonstrate that the model developed by Fisk and Schwadron (Astrophys. J.
560, 425, 2001) of interchange reconnections between “open” magnetic field and small coronal loops is a strong candidate for the mechanism
facilitating the recovery of the dimmings. This process disperses the concentration of “open” magnetic field (forming the
dimming) out into the surrounding quiet Sun, thus recovering the intensity of the dimmings whilst still maintaining the magnetic
connectivity to the Sun.
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献
17.
The period of 10–14 July 2000 saw a large number of energetic solar events ending with a very energetic flare that was associated with a large solar energetic particle event and a fast halo coronal mass ejection (CME) that produced the largest geomagnetic disturbance since 1989. This paper tries to summarize the complex coronal activity observed during this period, in order to establish a background for a number of papers in this topical issue. The GOES X-ray data are presented. Data animations of observations from EIT and LASCO C2 and C3 are presented on the accompanying CD-ROM. The observations around the time of the three X-class flares are considered. EIT observations of the Bastille Day flare show coronal brightening followed by dimming. LASCO had good data coverage for all three events. For one of the flares, no coronal response was seen. The other two flares are associated with halo CMEs. The timing suggests that the start of the flares and CMEs are simultaneous to approximately 30 min. Analysis of the LASCO and EIT images following the Bastille Day flare show the arrival of energetic particles at SOHO at approximately 10:41 UT on 14 July. Individual features of these CMEs have been tracked and the height–time plots used to estimate the dynamics of the CMEs. The initial speed and deceleration of the halo CMEs estimated from the fitting of height–time plots are compared with the in-situ observations at L1. The three flares are identified as the solar sources of three shocks observed at 1 AU. Finally, it is stressed that global heliospheric effects during periods of exceptional activity should consider a cumulative scenario rather than events in isolation. 相似文献
18.
19.
M. Mierla B. Inhester C. Marqué L. Rodriguez S. Gissot A. N. Zhukov D. Berghmans J. Davila 《Solar physics》2009,259(1-2):123-141
The data from SECCHI-COR1 and SECCHI-COR2 coronagraphs onboard the STEREO mission, which was launched in October 2006, provide us with the first-ever stereoscopic images of the Sun’s corona. These observations were found to be useful in inferring the three-dimensional structure of coronal mass ejections (CMEs) and their propagation direction in space. We apply four methods for reconstructing CMEs: i) Forward modeling technique; ii) Local correlation tracking (to identify the same feature in COR Ahead and COR Behind images) plus tie-point reconstruction technique; iii) Center of mass of the structures in a given epipolar plane plus tie-point reconstruction technique; iv) Polarization ratio technique. The four techniques are applied to three structured CMEs observed by COR1 and COR2 instruments, respectively, on 15 May 2007, 31 August 2007, and 25 March 2008. A comparison of the results obtained from the application of the four reconstruction algorithms is presented and discussed. 相似文献
20.
Global extreme-ultraviolet (EUV) waves are spectacular traveling disturbances in the solar corona associated with energetic eruptions such as coronal mass ejections (CMEs) and flares. Over the past 15 years, observations from three generations of space-borne EUV telescopes have shaped our understanding of this phenomenon and at the same time led to controversy about its physical nature. Since its launch in 2010, the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) has observed more than 210 global EUV waves in exquisite detail, thanks to its high spatio–temporal resolution and full-disk, wide-temperature coverage. A combination of statistical analysis of this large sample, more than 30 detailed case studies, and data-driven MHD modeling, has been leading their physical interpretations to a convergence, favoring a bimodal composition of an outer, fast-mode magnetosonic wave component and an inner, non-wave CME component. Adding to this multifaceted picture, AIA has also discovered new EUV wave and wave-like phenomena associated with various eruptions, including quasi-periodic fast propagating (QFP) wave trains, magnetic Kelvin–Helmholtz instabilities (KHI) in the corona and associated nonlinear waves, and a variety of mini-EUV waves. Seismological applications using such waves are now being actively pursued, especially for the global corona. We review such advances in EUV wave research focusing on recent SDO/AIA observations, their seismological applications, related data-analysis techniques, and numerical and analytical models. 相似文献