Long‐duration hectometric type III radio bursts and their association with solar energetic particle (SEP) events

MacDowall, R. J.; Lara, A.; Manoharan, P. K.; Nitta, N.; Rosas, Alexandre; Bougeret, Jean‐Louis

doi:10.1029/2002gl016624

Cited by 40 publications

(34 citation statements)

References 8 publications

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“…The associated SEP events were clearly detected by GOES, even if the particle intensity was weak. This confirms the fact that flares, CMEs, metre wave type IV bursts and bright groups of DH type III bursts are necessarily associated with major SEP events, as observed by GOES, in line with earlier findings by Kahler (1982) for the type IV bursts and Cane, Erickson, and Prestage (2002) and MacDowall et al (2003) for the DH type III bursts. The situation is not the same for impulsive SEP events, which may occur without type IV emission, as shown in Klassen et al (2002), Maia and Pick (2004), and Klein and Posner (2005).…”

Section: Discussionsupporting

confidence: 91%

Energetic Particle Acceleration and Propagation in Strong CME-Less Flares

2010

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Flares and coronal mass ejections (CMEs) contribute to the acceleration and propagation of solar energetic particles (SEP) detected in the interplanetary space, but the exact roles of these phenomena are yet to be understood. We examine two types of energetic particle tracers related with 15 CME-less flares that emit bright soft X-ray bursts (GOES X class): radio emission of flare-accelerated electrons and in situ measurements of energetic electrons and protons near 1 AU. The CME-less flares are found to be vigorous accelerators of microwave-emitting electrons, which remain confined in low coronal structures. This is shown by unusually steep low-frequency microwave spectra and by lack of radio emission from the middle and high corona, including dm -m wave type IV continua and metre-tohectometre type III bursts. The confinement of the particles accelerated in CME-less flares agrees with the magnetic field configuration of these events inferred by others. Two events produced isolated metric type II bursts revealing coronal shock waves. None of the seven flares in the western hemisphere was followed by enhanced particle fluxes in the GOES detectors, but one, which was accompanied by a type II burst, caused a weak SEP event detected at SoHO and ACE. Three of the CME-less flares were followed within some hours by SEP-associated flares from the same active region. These SEP-producing events were clearly distinct from the CME-less ones by their association with fast and broad CMEs, dm -m wave radio emission, and intense DH type III bursts. We conclude that radio emission at decimetre and longer waves is a reliable indication that flare-accelerated particles have access to the high corona and interplanetary space. The absence of such emission can be used as a signal that no SEP event is to be expected despite the occurrence of a strong soft X-ray burst.

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Section: Discussionsupporting

confidence: 91%

Energetic Particle Acceleration and Propagation in Strong CME-Less Flares

2010

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“…Cane et al (2002) suggested that the complex type III bursts are indicative of large SEP events. MacDowall et al (2003MacDowall et al ( , 2009) confirmed the type III-SEP association. These association studies were thought to imply a flare acceleration mechanism for the SEP events.…”

Section: Low-frequency Type III Bursts Associated With Glessupporting

confidence: 56%

Properties of Ground Level Enhancement Events and the Associated Solar Eruptions During Solar Cycle 23

et al. 2012

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Solar cycle 23 witnessed the most complete set of observations of coronal mass ejections (CMEs) associated with the Ground Level Enhancement (GLE) events. We present an overview of the observed properties of the GLEs and those of the two associated phenomena, viz., flares and CMEs, both being potential sources of particle acceleration. Although we do not find a striking correlation between the GLE intensity and the parameters of flares and CMEs, the solar eruptions are very intense involving X-class flares and extreme CME speeds (average ∼2000 km/s). An M7.1 flare and a 1200 km/s CME are the weakest events in the list of 16 GLE events. Most (80 %) of the CMEs are full halos with the three nonhalos having widths in the range 167 to 212 degrees. The active regions in which the GLE events originate are generally large: 1290 msh (median 1010 msh) compared to 934 msh (median: 790 msh) for SEP-producing active regions. For accurate estimation of the CME height at the time of metric type II onset and GLE particle release, we estimated the initial acceleration of the CMEs using flare and CME observations. The initial acceleration of GLE-associated CMEs is much larger (by a factor of 2) than that of ordinary CMEs (2.3 km/s 2 vs. 1 km/s 2 ). We confirmed the initial acceleration for two events for which CME measurements are available in the inner corona. The GLE particle release is delayed with respect to the onset of all electromagnetic signatures of the eruptions: type II bursts, low frequency type III bursts, soft X-ray flares and CMEs. The presence of metric type II radio bursts some 17 min (median: 16 min; range: 3 to 48 min) before the GLE onset indicates shock formation well before the particle release. The release of GLE particles occurs when the CMEs reach an average height of ∼3.09 R s (median: 3.18 R s ; range: 1.71 to 4.01 R s ) for well-connected events (source longitude in the range W20-W90). events, the average CME height at GLE particle release is ∼66 % larger (mean: 5.18 R s ; median: 4.61 R s ; range: 2.75-8.49 R s ). The longitudinal dependence is consistent with shock accelerations because the shocks from poorly connected events need to expand more to cross the field lines connecting to an Earth observer. On the other hand, the CME height at metric type II burst onset has no longitudinal dependence because electromagnetic signals do not require magnetic connectivity to the observer. For several events, the GLE particle release is very close to the time of first appearance of the CME in the coronagraphic field of view, so we independently confirmed the CME height at particle release. The CME height at metric type II burst onset is in the narrow range 1.29 to 1.8 R s , with mean and median values of 1.53 and 1.47 R s . The CME heights at metric type II burst onset and GLE particle release correspond to the minimum and maximum in the Alfvén speed profile. The increase in CME speed between these two heights suggests an increase in Alfvénic Mach number from 2 to 3. The CME heights at GLE particle r...

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“…Earlier works report large occurrence rates of metric (∼90%) and DH type II bursts (100%) when associated with strong or major proton events, see e.g., Gopalswamy (2003); Cliver et al (2004); Cliver and Ling (2007). Interestingly, the same rates are reported for metric (100%) and DH type III bursts (∼90%) by Cane et al (2002);MacDowall et al (2003), respectively, again in relation to protons with large intensities. In a comprehensive analysis over SC23, Miteva et al (2013b) reported that the association between ∼25 MeV proton events and the DH type III is always present, followed by m and DH-II (75%) and m-IV (about 60%) bursts, see also their Table 4.…”

Section: Introductionsupporting

confidence: 53%

Solar energetic particles and radio burst emission

Miteva

Samwel

Krupař

2017

J. Space Weather Space Clim.

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-We present a statistical study on the observed solar radio burst emission associated with the origin of in situ detected solar energetic particles. Several proton event catalogs in the period 1996-2016 are used. At the time of appearance of the particle origin (flare and coronal mass ejection) we identified radio burst signatures of types II, III and IV by inspecting dynamic radio spectral plots. The information from observatory reports is also accounted for during the analysis. The occurrence of solar radio burst signatures is evaluated within selected wavelength ranges during the solar cycle 23 and the ongoing 24. Finally, we present the burst occurrence trends with respect to the intensity of the proton events and the location of their solar origin.

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Long‐duration hectometric type III radio bursts and their association with solar energetic particle (SEP) events

Cited by 40 publications

References 8 publications

Energetic Particle Acceleration and Propagation in Strong CME-Less Flares

Energetic Particle Acceleration and Propagation in Strong CME-Less Flares

Properties of Ground Level Enhancement Events and the Associated Solar Eruptions During Solar Cycle 23

Solar energetic particles and radio burst emission

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