Highly relativistic electron flux enhancement during the weak geomagnetic storm of April-May 2017

We report observations of energetic electron flux and Phase Space Density (PSD) to show that a relatively weak magnetic storm with \(Sym-H_{min} \approx -50 \)nT, resulted in a relativistic and ultra--relativistic electron enhancement of two orders of magnitude similar to the St. Patrick's even...

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Bibliographic Details
Published in:arXiv.org 2019-02
Main Authors: Katsavrias, Christos, Sandberg, Ingmar, Li, Wen, Podladchikova, Olena, Daglis, Ioannis A, Papadimitriou, Constantinos, Tsironis, Christos, Aminalragia-Giamini, Sigiava
Format: Article
Language:English
Subjects:
Electron density
Geomagnetism
Geosynchronous orbits
Magnetic storms
Relativism
Relativistic effects
Space density
Online Access:Get full text
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Summary:We report observations of energetic electron flux and Phase Space Density (PSD) to show that a relatively weak magnetic storm with \(Sym-H_{min} \approx -50 \)nT, 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 \(Sym-H_{min} \approx -235 nT\). This enhancement appeared at energies up to \(\approx 10\) 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.
ISSN:2331-8422
DOI:10.48550/arxiv.1902.00960