Combined effects of concurrent Pc5 and chorus waves on relativistic electron dynamics

Katsavrias, Christos; Daglis, Ioannis A.; Li, W.; Dimitrakoudis, Stavros; Γεωργίου, Μαρίνα; Turner, D. L.; Papadimitriou, Constantinos

doi:10.5194/angeo-33-1173-2015

Cited by 16 publications

(19 citation statements)

References 44 publications

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“…Note that the maximum chorus amplitude also moved from L ≈4.7 to L * ≈6.3 during 21–25 April. This result is consistent with the findings of Katsavrias, Daglis, Li, et al () who showed that, during the March 2013 intense storm and concerning the >300‐MeV/G electrons, the chorus‐driven acceleration exceeded the Pc5‐driven losses. After 24 April, PSD gradients were continuously positive with gradual decrease.…”

Section: Resultssupporting

confidence: 92%

Highly Relativistic Electron Flux Enhancement During the Weak Geomagnetic Storm of April–May 2017

Katsavrias

Sandberg²,

et al. 2019

JGR Space Physics

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Key Points:• Long-lasting multi-MeV electron enhancement during a period of a relatively weak geomagnetic storm not recorded in GEO. • Electron seed population was accelerated to relativistic energies by the enhanced chorus waves. • Relativistic electrons were further accelerated up to 10 MeV by inward diffusion Corresponding author: Ch. Katsavrias, ckatsavrias@phys.uoa.grWe report observations of energetic electron flux and Phase Space Density (PSD) to show that a relatively weak magnetic storm with Sym−H min ≈ −50nT, resulted in a relativistic and ultra-relativistic electron enhancement of two orders of magnitude similar to the St. Patrick's event of 2015, an extreme storm with Sym − H min ≈ −235nT. This enhancement appeared at energies up to ≈ 10 MeV, lasted for at least 24 days and was not recorded in geosynchronous orbit where most space weather alert data are collected. By combined analysis of PSD radial profiles and Fokker-Planck simulation, we show that the enhancement of relativistic and ultra-relativistic electrons is caused by different mechanisms: first, chorus waves during the intense substorm injections of April 21-25 accelerate the seed electron population to relativistic energies and redistribute them while inward diffusion driven by Pc5 ULF waves further accelerates them to ultra-relativistic energies.

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Section: Resultssupporting

confidence: 92%

Highly Relativistic Electron Flux Enhancement During the Weak Geomagnetic Storm of April–May 2017

Katsavrias

Sandberg²,

et al. 2019

JGR Space Physics

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“…We note similar results by Katsavrias et al (2015), who examined only a single EA and IA event, and that of Ma et al (2018) but without a discussion on morphological similarities. We note similar results by Katsavrias et al (2015), who examined only a single EA and IA event, and that of Ma et al (2018) but without a discussion on morphological similarities.…”

Section: Discussionsupporting

confidence: 81%

On the Close Correspondence Between Storm Time ULF Wave Power and the POES VLF Chorus Wave Amplitude Proxy

Dimitrakoudis

Mann

2019

Geophysical Research Letters

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Ground‐based Pc5 ultralow frequency (ULF) wave power in multiple ground‐based meridians is compared to the very low frequency (VLF) wave amplitude proxy, derived from Polar Operational Environmental Satellite (POES) precipitation, for the 33 storms studied by Li et al. (2015, https://doi.org/10.1002/2015GL065342). The results reveal common L‐shell and time profiles for the ULF waves and VLF proxy for every single storm, especially at L ≤ 6, and identical discrimination between efficient and inefficient radiation belt electron acceleration. The observations imply either ULF waves play a role in driving precipitation, which is falsely interpreted as VLF wave power in the proxy, ULF waves drive VLF waves (the reverse being energetically unfeasible), or both have a common driver with nearly identical L‐shell and time dependence. Global ground‐based ULF wave power coherence implies that a small number of meridians can be used to estimate storm time radial diffusion coefficients. However, the strong correspondence between ULF wave power and VLF wave proxy complicates causative assessments of electron acceleration.

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“…of Figure 16 we observe that, during storm time, ULF power in the range of Pc5 (2-7 mHz) across the magnetosphere increases by two to three orders of magnitude, leading to a corresponding enhancement of the diffusion coefficients of >300 keV electrons, and hence to enhanced outward diffusion (Mann et al 2012;Katsavrias et al 2015). Since ULF wave power is correlated with the solar-wind dynamic pressure (e.g., Kepko & Spence 2003;Liu et al 2010), we can expect that the magnetospheric compression caused by the arrival of the IP shock at 1 AU (see Section 6.1) could have led to the observed enhancement of ULF waves, which in turn contributed to the observed radial losses of relativistic particles.…”

Section: Radiation Belt Dynamicsmentioning

confidence: 89%

The Major Geoeffective Solar Eruptions of 2012 March 7: Comprehensive Sun-to-Earth Analysis

Patsourakos

Georgoulis

Vourlidas

et al. 2016

ApJ

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During the interval 2012 March 7-11 the geospace experienced a barrage of intense space weather phenomena including the second largest geomagnetic storm of solar cycle 24 so far. Significant ultra-low-frequency wave enhancements and relativistic-electron dropouts in the radiation belts, as well as strong energetic-electron injection events in the magnetosphere were observed. These phenomena were ultimately associated with two ultra-fast (>2000 km s −1 ) coronal mass ejections (CMEs), linked to two X-class flares launched on early 2012 March 7. Given that both powerful events originated from solar active region NOAA 11429 and their onsets were separated by less than an hour, the analysis of the two events and the determination of solar causes and geospace effects are rather challenging. Using satellite data from a flotilla of solar, heliospheric and magnetospheric missions a synergistic Sun-to-Earth study of diverse observational solar, interplanetary and magnetospheric data sets was performed. It was found that only the second CME was Earth-directed. Using a novel method, we estimated its near-Sun magnetic field at 13 R e to be in the range [0.01, 0.16] G. Steep radial fall-offs of the near-Sun CME magnetic field are required to match the magnetic fields of the corresponding interplanetary CME (ICME) at 1 AU. Perturbed upstream solar-wind conditions, as resulting from the shock associated with the Earth-directed CME, offer a decent description of its kinematics. The magnetospheric compression caused by the arrival at 1 AU of the shock associated with the ICME was a key factor for radiation-belt dynamics.

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Combined effects of concurrent Pc5 and chorus waves on relativistic electron dynamics

Cited by 16 publications

References 44 publications

Highly Relativistic Electron Flux Enhancement During the Weak Geomagnetic Storm of April–May 2017

Highly Relativistic Electron Flux Enhancement During the Weak Geomagnetic Storm of April–May 2017

On the Close Correspondence Between Storm Time ULF Wave Power and the POES VLF Chorus Wave Amplitude Proxy

The Major Geoeffective Solar Eruptions of 2012 March 7: Comprehensive Sun-to-Earth Analysis

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