A Twin-CME Scenario for Ground Level Enhancement Events

Li, Gang; Moore, Ronald L.; Mewaldt, R. A.; Zhao, Lulu; Labrador, A. W.

doi:10.1007/s11214-011-9823-7

Cited by 115 publications

(138 citation statements)

References 54 publications

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“…However, if a southward-pointing magnetic field associated with an intense CME event reconnects with the geomagnetic field, an unusually large fraction of the atmosphere may be exposed to particles accelerated efficiently by the shock wave associated with a closely following second CME (Li et al 2012). The synergistic effects of reduced geomagnetic cutoffs and hard SEP spectra could lead to unusually effective production of 14 C and other cosmogenic isotopes, and hence the calculated values for the required particle fluences may be too large.…”

Section: Resultsmentioning

confidence: 99%

“…Examples include the August 4, 1972, and July 14, 2000, events, among the largest of the space era. In addition, Gopalswamy et al (2004) and Li et al (2012) have shown that many CMEs involving especially high fluences of SEPs are twin events where a second CME erupts within 24 hours of the first. The 14 C production from the two events would add nearly linearly (Melott et al 2012).…”

Section: Solar Proton Events and Coronal Mass Ejectionsmentioning

confidence: 99%

“…Twin CMEs occur relatively frequently (Li et al 2012;Ding et al 2013) and multiple large events within a few days (often from the same active region) are common. Gopalswamy et al (2004) reported that most of the large SEP events originating from CMEdriven shock acceleration in 1997 to early 2002 were preceded by an earlier CME-driven shock event originating from the same solar active region within 24 hours earlier.…”

Section: Solar Proton Events and Coronal Mass Ejectionsmentioning

confidence: 99%

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Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC

et al. 2017

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ABSTRACT. Since the AD 775 and AD 994 Δ 14 C peak (henceforth M12) was first measured by Miyake et al. (2012Miyake et al. ( , 2013, several possible production mechanisms for these spike have been suggested, but the work of Mekhaldi et al. (2015) shows that a very soft energy spectrum was involved, implying that a strong solar energetic particle (SEP) event (or series of events) was responsible. Here we present Δ 14 C values from AD 721-820 Sequoiadendron giganteum annual tree-ring samples from Sequoia National Park in California, USA, together with Δ 14 C in German oak from 650-670 BC. The AD 721-820 measurements confirm that a sharp Δ 14 C peak exists at AD 775, with a peak height of approximately 15‰ and show that this spike was preceded by several decades of rapidly decreasing Δ 14 C. A sharp peak is also present at 660 BC, with a peak height of about 10‰, and published data ) indicate that it too was preceded by a multi-decadal Δ 14 C decrease, suggesting that solar activity was very strong just prior to both Δ 14 C peaks and may be causally related. During periods of strong solar activity there is increased probability for coronal mass ejection (CME) events that can subject the Earth's atmosphere to high fluencies of solar energetic particles (SEPs). Periods of high solar activity (such as one in October-November 2003) can also often include many large, fast CMEs increasing the probability of geomagnetic storms. In this paper we suggest that the combination of large SEP events and elevated geomagnetic activity can lead to enhanced production of 14 C and other cosmogenic isotopes by increasing the area of the atmosphere that is irradiated by high solar energetic particles.

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Section: Resultsmentioning

confidence: 99%

Section: Solar Proton Events and Coronal Mass Ejectionsmentioning

confidence: 99%

Section: Solar Proton Events and Coronal Mass Ejectionsmentioning

confidence: 99%

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Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC

et al. 2017

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“…However, not all CMEs that satisfy the two factors can lead to large SEP events or GLEs (e.g., Kahler & Vourlidas 2005;Ding et al 2013), indicating other processes are important for producing large SEP events as well. The proposed factors include the background energetic particles that provide seed particles for the shock acceleration to high energies (e.g., Kahler et al 2000;Kahler 2001;Cliver 2006), preceding CMEs that may provide both seed particles and enhanced turbulence for more efficient particle acceleration (e.g., Gopalswamy et al 2004;Li et al 2012;Ding et al 2013;Zhao & Li 2014), and the CME shock geometry that allows a perpendicular shock region to rapidly accelerate particles to high energies (e.g., Tylka et al 2005). …”

Section: Introductionmentioning

confidence: 99%

The Acceleration of High-energy Protons at Coronal Shocks: The Effect of Large-scale Streamer-like Magnetic Field Structures

Kong

Guo

Giacalone

et al. 2017

ApJ

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Recent observations have shown that coronal shocks driven by coronal mass ejections can develop and accelerate particles within several solar radii in large solar energetic particle (SEP) events. Motivated by this, we present an SEP acceleration study that including the process in which a fast shock propagates through a streamer-like magnetic field with both closed and open field lines in the low corona region. The acceleration of protons is modeled by numerically solving the Parker transport equation with spatial diffusion both along and across the magnetic field. We show that particles can be sufficiently accelerated to up to several hundred MeV within 2-3 solar radii. When the shock propagates through a streamer-like magnetic field, particles are more efficiently accelerated compared to the case with a simple radial magnetic field, mainly due to perpendicular shock geometry and the natural trapping effect of closed magnetic fields. Our results suggest that the coronal magnetic field configuration is an important factor for producing large SEP events. We further show that the coronal magnetic field configuration strongly influences the distribution of energetic particles, leading to different locations of source regions along the shock front where most high-energy particles are concentrated. This work may have strong implications for SEP observations. The upcoming Parker Solar Probe will provide in situ observations for the distribution of energetic particles in the coronal shock region, and test the results of the study.

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“…The preceding CME may perform pre-conditioning in two ways: to provide seed particles to be re-accelerated at the shock driven by the main CME (Kahler 2001;Cliver et al 1983;Cliver 2006), and to cause higher level of turbulence in the upstream region of the main CME (Li and Zank 2005). Recently Li et al (2011) have further developed the concept of double CMEs occurring close in time that may lead to enhanced particle acceleration.…”

Section: Introductionmentioning

confidence: 99%

What Are Special About Ground-Level Events?

et al. 2012

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Ground level events (GLEs) occupy the high-energy end of gradual solar energetic particle (SEP) events. They are associated with coronal mass ejections (CMEs) and solar flares, but we still do not clearly understand the special conditions that produce these rare events. During Solar Cycle 23, a total of 16 GLEs were registered, using ground-based neutron monitor data. We first ask if these GLEs are clearly distinguishable from other SEP events observed from space. Setting aside possible difficulties in identifying all GLEs consistently, we then try to find observables which may unmistakably isolate these GLEs by studying the basic properties of the associated eruptions and the active regions (ARs) that produced them. It is found that neither the magnitudes of the CMEs and flares nor the complexities of the ARs give sufficient conditions for GLEs. It is possible to find CMEs, flares or ARs that are not associated with GLEs but that have more extreme properties than those associated with GLEs. We also try to evaluate the importance of magnetic field connection of the AR with Earth on the detection of GLEs and their onset times. Using the potential field source surface (PFSS) model, a half of the GLEs are found to be well-connected. However, the GLE onset time with respect to the onset of the associated flare and CME does not strongly depend on how well-connected the AR is. The GLE onset behavior may be largely determined by when and where the CME-driven shock develops. We could not relate the shocks responsible for the onsets of past GLEs with features in solar images, but the combined data from the Solar TErrestrial RElations Observatory (STEREO) and the Solar Dynamics Observatory (SDO) have the potential to change this for GLEs that may occur in the rising phase of Solar Cycle 24.

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A Twin-CME Scenario for Ground Level Enhancement Events

Cited by 115 publications

References 54 publications

Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC

Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC

The Acceleration of High-energy Protons at Coronal Shocks: The Effect of Large-scale Streamer-like Magnetic Field Structures

What Are Special About Ground-Level Events?

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A Twin-CME Scenario for Ground Level Enhancement Events

Cited by 115 publications

References 54 publications

Relationship between solar activity and Δ14C peaks in AD 775, AD 994, and 660 BC

Relationship between solar activity and Δ14C peaks in AD 775, AD 994, and 660 BC

The Acceleration of High-energy Protons at Coronal Shocks: The Effect of Large-scale Streamer-like Magnetic Field Structures

What Are Special About Ground-Level Events?

Contact Info

Product

Resources

About

Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC

Relationship between solar activity and Δ¹⁴C peaks in AD 775, AD 994, and 660 BC