Coronal mass ejections of solar cycle 23
TL;DR: In this paper, the statistical, physical, and morphological properties of coronal mass ejections (CMEs) of solar cycle 23, as observed by the Solar and Heliospheric Observatory (SOHO) mission are summarized.
Abstract: I summarize the statistical, physical, and morphological properties of coronal mass ejections (CMEs) of solar cycle 23, as observed by the Solar and Heliospheric Observatory (SOHO) mission. The SOHO data is by far the most extensive data, which made it possible to fully establish the properties of CMEs as a phenomenon of utmost importance to Sun-Earth connection as well as to the heliosphere. I also discuss various subsets of CMEs that are of primary importance for their impact on Earth.
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TL;DR: The SOHO/LASCO CME catalog as mentioned in this paper is a data base for the analysis of coronal mass ejections (CMEs) in the solar corona.
Abstract: Coronal mass ejections (CMEs) are routinely identified in the images of the solar corona obtained by the Solar and Heliospheric Observatory (SOHO) mission’s Large Angle and Spectrometric Coronagraph (LASCO) since 1996. The identified CMEs are measured and their basic attributes are cataloged in a data base known as the SOHO/LASCO CME Catalog. The Catalog also contains digital data, movies, and plots for each CME, so detailed scientific investigations can be performed on CMEs and the related phenomena such as flares, radio bursts, solar energetic particle events, and geomagnetic storms. This paper provides a brief description of the Catalog and summarizes the statistical properties of CMEs obtained using the Catalog. Data products relevant to space weather research and some CME issues that can be addressed using the Catalog are discussed. The URL of the Catalog is: http://cdaw.gsfc.nasa.gov/CME_list.
587 citations
Cites result from "Coronal mass ejections of solar cyc..."
...Earlier results can be found in Gopalswamy (2004), Yashiro et al. (2004), and Gopalswamy (2006)....
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George Mason University1, University of Maryland, College Park2, Goddard Space Flight Center3, Boston College4, University of California, Berkeley5, Massachusetts Institute of Technology6, University of Alabama in Huntsville7, The Catholic University of America8, Royal Observatory of Belgium9, Moscow State University10
TL;DR: In this article, the authors presented the results of an investigation of the sequence of events from the Sun to the Earth that ultimately led to the 88 major geomagnetic storms (defined by minimum Dst �� 100 nT) that occurred during 1996-2005.
Abstract: [1] We present the results of an investigation of the sequence of events from the Sun to the Earth that ultimately led to the 88 major geomagnetic storms (defined by minimum Dst �� 100 nT) that occurred during 1996–2005. The results are achieved through cooperative efforts that originated at the Living with a Star (LWS) Coordinated DataAnalysis Workshop (CDAW) held at George Mason University in March 2005. On the basis of careful examination of the complete array of solar and in situ solar wind observations, we have identified and characterized, for each major geomagnetic storm, the overall solar-interplanetary (solar-IP) source type, the time, velocity, and angular width of the source coronal mass ejection (CME), the type and heliographic location of the solar source region, the structure of the transient solar wind flow with the storm-driving component specified, the arrival time of shock/disturbance, and the start and ending times of the corresponding IP CME (ICME). The storm-driving component, which possesses a prolonged and enhanced southward magnetic field (Bs), may be an ICME, the sheath of shocked plasma (SH) upstream of an ICME, a corotating interaction region (CIR), or a combination of these structures. We classify the Solar-IP sources into three broad types: (1) S-type, in which the storm is associated with a single ICME and a single CME at the Sun; (2) M-type, in which the storm is associated with a complex solar wind flow produced by multiple interacting ICMEs arising from multiple halo CMEs launched from the Sun in a short period; (3) C-type, in which the storm is associated with a CIR formed at the leading edge of a high-speed stream originating from a solar coronal hole (CH). For the 88 major storms, the S-type, M-type, and C-type events number 53 (60%), 24 (27%), and 11 (13%), respectively. For the 85 events for which the surface source regions could be investigated, 54 (63%) of the storms originated in solar active regions, 11 (13%) in quiet Sun regions associated with quiescent filaments or filament channels, and 11 (13%) were associated with coronal holes. Remarkably, nine (11%) CME-driven events showed no sign of eruptive features on the surface or in the low corona (e.g., no flare, no coronal dimming, and no loop arcade, etc.), even though all the available solar observations in a suitable time period were carefully examined. Thus while it is generally true that a major geomagnetic storm is more likely to be driven by a frontside fast halo CME associated with a major flare, our study indicates a broad distribution of source properties. The implications of the results for space weather forecasting are briefly discussed.
540 citations
TL;DR: In this paper, the authors evaluated the energy of 38 solar eruptive events observed by a variety of spacecraft instruments between 2002 February and 2006 December, as accurately as the observations allow.
Abstract: We have evaluated the energetics of 38 solar eruptive events observed by a variety of spacecraft instruments between 2002 February and 2006 December, as accurately as the observations allow. The measured energetic components include: (1) the radiated energy in the Geostationary Operational Environmental Satellite 1-8 A band, (2) the total energy radiated from the soft X-ray (SXR) emitting plasma, (3) the peak energy in the SXR-emitting plasma, (4) the bolometric radiated energy over the full duration of the event, (5) the energy in flare-accelerated electrons above 20 keV and in flare-accelerated ions above 1 MeV, (6) the kinetic and potential energies of the coronal mass ejection (CME), (7) the energy in solar energetic particles (SEPs) observed in interplanetary space, and (8) the amount of free (non-potential) magnetic energy estimated to be available in the pertinent active region. Major conclusions include: (1) the energy radiated by the SXR-emitting plasma exceeds, by about half an order of magnitude, the peak energy content of the thermal plasma that produces this radiation; (2) the energy content in flare-accelerated electrons and ions is sufficient to supply the bolometric energy radiated across all wavelengths throughout the event; (3) the energy contents of flare-accelerated electrons and ions are comparable; (4) the energy in SEPs is typically a few percent of the CME kinetic energy (measured in the rest frame of the solar wind); and (5) the available magnetic energy is sufficient to power the CME, the flare-accelerated particles, and the hot thermal plasma.
452 citations
TL;DR: This paper provides a comprehensive review of the current state of knowledge of these important phenomena, and summarizes some of the key questions that will be addressed by two upcoming missions—NASA's Solar Probe Plus and ESA's Solar Orbiter.
Abstract: Solar energetic particles, or SEPs, from suprathermal (few keV) up to relativistic (
$$\sim $$
few GeV) energies are accelerated near the Sun in at least two ways: (1) by magnetic reconnection-driven processes during solar flares resulting in impulsive SEPs, and (2) at fast coronal-mass-ejection-driven shock waves that produce large gradual SEP events. Large gradual SEP events are of particular interest because the accompanying high-energy (
$${>}10$$
s MeV) protons pose serious radiation threats to human explorers living and working beyond low-Earth orbit and to technological assets such as communications and scientific satellites in space. However, a complete understanding of these large SEP events has eluded us primarily because their properties, as observed in Earth orbit, are smeared due to mixing and contributions from many important physical effects. This paper provides a comprehensive review of the current state of knowledge of these important phenomena, and summarizes some of the key questions that will be addressed by two upcoming missions—NASA’s Solar Probe Plus and ESA’s Solar Orbiter. Both of these missions are designed to directly and repeatedly sample the near-Sun environments where interplanetary scattering and transport effects are significantly reduced, allowing us to discriminate between different acceleration sites and mechanisms and to isolate the contributions of numerous physical processes occurring during large SEP events.
335 citations
Cites background or methods from "Coronal mass ejections of solar cyc..."
...(2005b, 2008) also found that the so-called GLE events were associated with ∼30 % of the very energetic CMEs with kinetic energies 1.2 × 1032 ergs (also see Gopalswamy 2006). The largest SEP events are associated with the fastest ∼1–2 % of CMEs. The CMEs have typical speeds >1500 km/s, although a few have speeds as low as ∼700–800 km/s (Kahler 2001). Figure 9 compares the mass (left) and energy (right) distributions of all CMEs (in blue) with those associated with 23 of the 50 largest SEP events (in red) from solar cycle 23. Similarly, Yurchyshyn et al. (2005) found that the distributions of the plane-of-sky-speeds for >4000 CMEs, whether they are accelerating or decelerating, showed no physical distinction and exhibited log-normal forms similar to the ones shown in Fig....
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...8 Scatter-plot of CME kinetic energy versus SEP kinetic energy for 23 large SEP events from solar cycle 23. Image adapted from Mewaldt et al. (2008)...
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...15 Hourly averaged intensity of suprathermal ∼30 keV/nucleon Fe (red) and number density of solar wind Fe (blue) during a 100-day period in 2004. Image reproduced with permission from Mason et al. (2005), copyright by AIP...
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...(1963) proposed that the energetic particles might be accelerated at magnetohydrodynamic shock waves that typically accompanied the flares. Later, Lin (1970) reported close associations between...
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...9 Left Comparison of the mass distribution of all CMEs observed from 1996–2003 (Gopalswamy 2006) to the masses of CMEs associated with 23 of the 50 largest SEP events of solar cycle 23 (scaled up by 20). Right Comparison between the distributions of the kinetic energy of CMEs associated with 23 large SEP events from solar cycle 23 and all CMEs observed from 1996–2003. Images reproduced with permission from Mewaldt et al. (2008), copyright by AIP...
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TL;DR: In this paper, the authors studied the geoeffectiveness, speed, solar source, and flare association of a set of 378 halo coronal mass ejections (CMEs) of cycle 23 (1996-2005, inclusive).
Abstract: [1] We studied the geoeffectiveness, speed, solar source, and flare association of a set of 378 halo coronal mass ejections (CMEs) of cycle 23 (1996–2005, inclusive). We compiled the minimum Dst values occurring within 1–5 days after the CME onset. We compared the distributions of such Dst values for the following subsets of halo CMEs: disk halos (within 45 deg from disk center), limb halos (beyond 45 degrees but within 90 deg from disk center), and backside halo CMEs. Defining that a halo CME is geoeffective if it is followed by Dst ≤ −50 nT, moderately geoeffective if −50 nT < Dst < −100 nT, and strongly geoeffective if Dst ≤ −100 nT, we find that the disk halos are followed by strong storms, limb halos are followed by moderate storms, and backside halos are not followed by significant storms. The Dst distribution for a random sample is nearly identical to the case of backside halos. About 71% of all frontside halos are geoeffective, supporting the high rate of geoeffectiveness of halo CMEs. A larger fraction (75%) of disk halos are geoeffective. Intense storms are generally due to disk halos and the few intense storms from limb halos occur only in the maximum and declining phases. Most intense storms occur when there are successive CMEs. The delay time between CME onset and minimum Dst value is the smallest for limb halos, suggesting that the sheath is geoeffective in these cases. The geoeffectiveness rate has prominent dips in 1999 and 2002 (the beginning and end years of the solar maximum phase). The numbers of all frontside and geoeffective frontside halos show a triple peak structure similar to the number of intense geomagnetic storms. The difference in flare sizes among geoeffective and nongeoeffective halos is not significant. The nongeoeffective CMEs are generally slower and have more easterly or limbward solar sources compared to the geoeffective ones; source location and speed are the most important parameters for geoeffectiveness.
207 citations
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TL;DR: The Large Angle Spectroscopic Coronagraph (LASCO) is a triple coronagraph being jointly developed for the Solar and Heliospheric Observatory (SOHO) mission as discussed by the authors.
Abstract: The Large Angle Spectroscopic Coronagraph (LASCO) is a triple coronagraph being jointly developed for the Solar and Heliospheric Observatory (SOHO) mission LASCO comprises three nested coronagraphs (C1, C2, and C3) that image the solar corona for 11 to 30 solar radii (C1: 11 to 3 solar radii, C2: 15 to 6 solar radii, and C3: 3 to 300 solar radii) The inner coronagraph (C1) is a newly developed mirror version of the classic Lyot coronagraph without an external occultor, while the middle coronagraph (C2) and the outer coronagraph (C3) are externally occulted instruments High resolution coronal spectroscopy from 11 to 3 R solar radii can be performed by using a Fabry-Perot interferometer, which is part of C1 High volume memories and a high speed microprocessor enable extensive onboard image processing Image compression by factors of 10 to 20 will result in the transmission of 10 to 20 full images per hour
2,476 citations
"Coronal mass ejections of solar cyc..." refers methods in this paper
...Here, I highlight the recent research on CMEs spurred by the extensive and uniform data from the Solar and Heliospheric Observatory (SOHO) mission’s Large Angle and Spectrometric Coronagraph (LASCO, Brueckner et al. 1995)....
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TL;DR: The Large Angle Spectroscopic Coronagraph (LASCO) is a three coronagraph package which has been jointly developed for the Solar and Heliospheric Observatory (SOHO) mission by the Naval Research Laboratory (USA), the Laboratoire d'Astronomie Spatiale (France), the Max-Planck-Institut fur Aeronomie (Germany), and the University of Birmingham (UK) as discussed by the authors.
Abstract: The Large Angle Spectroscopic Coronagraph (LASCO) is a three coronagraph package which has been jointly developed for the Solar and Heliospheric Observatory (SOHO) mission by the Naval Research Laboratory (USA), the Laboratoire d’Astronomie Spatiale (France), the Max-Planck-Institut fur Aeronomie (Germany), and the University of Birmingham (UK) LASCO comprises three coronagraphs, C1, C2, and C3, that together image the solar corona from 11 to 30 R⊙ (C1: 11–3 R⊙, C2: 15–6 R⊙, and C3: 37 – 30 R⊙) The C1 coronagraph is a newly developed mirror version of the classic internally-occulted Lyot coronagraph, while the C2 and C3 coronagraphs are externally occulted instruments High-resolution imaging spectroscopy of the corona from 11 to 3 R⊙ can be performed with the Fabry-Perot interferometer in C1 High-volume memories and a high-speed microprocessor enable extensive on-board image processing Image compression by a factor of about 10 will result in the transmission of 10 full images per hour
1,756 citations
"Coronal mass ejections of solar cyc..." refers methods in this paper
...Here, I highlight the recent research on CMEs spurred by the extensive and uniform data from the Solar and Heliospheric Observatory (SOHO) mission’s Large Angle and Spectrometric Coronagraph (LASCO, Brueckner et al. 1995)....
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TL;DR: The flow behind an interplanetary shock was analyzed through the use of magnetic field and plasma data from five spacecraft, with emphasis on the magnetic cloud identified by a characteristic variation of the latitude angle of the magnetic field.
Abstract: The flow behind an interplanetary shock was analyzed through the use of magnetic field and plasma data from five spacecraft, with emphasis on the magnetic cloud identified by a characteristic variation of the latitude angle of the magnetic field. The size of the cloud was found to be about 0.5 AU in radial extent and greater than 30 deg in azimuthal extent, with its front boundary almost normal to the radial direction. Because the field direction of the magnetic cloud as it moved past the spacecraft was observed to rotate nearly parallel to a plane, it is thought that the field configuration of the cloud was essentially two-dimensional. These results further suggest that the lines of force in the magnetic cloud formed loops, but it could not be determined whether these loops were open or closed.
1,575 citations
TL;DR: In this paper, the authors present a summary of the statistical properties of the CMEs, including the apparent central position angle, the angular width in the sky plane, and the height (heliocentric distance) as a function of time.
Abstract: [1] The Solar and Heliospheric Observatory (SOHO) mission's white light coronagraphs have observed nearly 7000 coronal mass ejections (CMEs) between 1996 and 2002. We have documented the measured properties of all these CMEs in an online catalog. We describe this catalog and present a summary of the statistical properties of the CMEs. The primary measurements made on each CME are the apparent central position angle, the angular width in the sky plane, and the height (heliocentric distance) as a function of time. The height-time measurements are then fitted to first- and second-order polynomials to derive the average apparent speed and acceleration of the CMEs. The statistical properties of CMEs are (1) the average width of normal CMEs (20° 900 km s−1) show deceleration. Solar cycle variation and statistical properties of CMEs are revealed with greater clarity in this study as compared with previous studies. Implications of our findings for CME models are discussed.
1,086 citations
"Coronal mass ejections of solar cyc..." refers background in this paper
...The measured sky-plane speed ranges from a few km s−1 to ∼3000 km s−1 (see e.g., Gopalswamy 2004; Yashiro et al. 2004), with an average value of ∼483 km s−1....
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TL;DR: In this paper, the authors outline a different paradigm of cause and effect that removes solar flares from their central position in the chain of events leading from the Sun to near-Earth space.
Abstract: Many years of research have demonstrated that large, nonrecurrent geomagnetic storms, shock wave disturbances in the solar wind, and energetic particle events in interplanetary space often occur in close association with large solar flares. This result has led to a pradigm of cause and effect - that large solar flares are the fundamental cause of these events in the near-Earth space environmemt. This paradigm, which I call 'the solar flare myth,' dominates the popular perception of the relationship between solar activity and interplanetary and geomagnetic events and has provided much of the pragmatic rationale for the study of the solar flare phenomenon. Yet there is good evidence that this paradigm is wrong and that flares do not generally play a central role in producing major transient disturbances in the near-Earth space environment. In this paper I outline a different paradigm of cause and effect that removes solar flares from their central position in the chain of events leading from the Sun to near-Earth space. Instead, this central role is given to events known as coronal mass ejections.
877 citations
"Coronal mass ejections of solar cyc..." refers background in this paper
...Gosling (1993) had pointed out the central role played by CMEs in causing intense geomagnetic storms....
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