000003549 001__ 3549
000003549 005__ 20190503170114.0
000003549 037__ $$aSCART-2018-0051
000003549 100__ $$aKatsavrias, Ch 
000003549 245__ $$aHighly relativistic electron flux enhancement during the weak geomagnetic storm of April–May 2017
000003549 260__ $$c2019
000003549 520__ $$aWe report observations of energetic electron flux and Phase Space Density (PSD) to show that a relatively weak magnetic storm with Sym − Hmin ≈ −50nT, resulted in a relativistic and ultra–relativistic electron enhancement of two orders of magnitude similar to the St.Patrick’s event of 2015, an extreme storm with Sym − Hmin ≈ −235nT. This enhancement appeared at energies up to ≈ 8 MeV, lasted for at least 24 days and was not recorded in geosynchronous orbit where most space weather alert data are collected. By analyzing radial profiles of PSD we show that the enhancement of relativistic and ultra–relativistic electrons is caused by different mechanisms: first, chorus waves during the intense substorm injections of April 21–25 accelerate the seed electron population to relativistic energies and redistribute them while inward diffusion driven by Pc5 ULF waves further accelerates them to ultra–relativistic energies.
000003549 594__ $$aSTCE
000003549 6531_ $$aLong–lasting multi–MeV electron enhancement during a period of a relatively weak
000003549 6531_ $$ageomagnetic storm.
000003549 6531_ $$aElectron seed population was accelerated to relativistic energies by the enhanced chorus waves.
000003549 6531_ $$aRelativistic electrons were further accelerated up to 8 MeV by inward diffusion.
000003549 700__ $$aSandberg, I
000003549 700__ $$aLi, W
000003549 700__ $$aPodladchikova, 0
000003549 700__ $$aDaglis, I
000003549 700__ $$aPapadimitriou, C 
000003549 700__ $$aAminalragia-Giamini, S
000003549 773__ $$pJournal Geophysical Research
000003549 8560_ $$felena.podladchikova@observatoire.be
000003549 905__ $$aaccepted to be published in
000003549 980__ $$aREFERD