title: Near-Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations.
abstract: Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector atL∼ 5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ∼40 s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L> 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.
authors.affiliation: State Key Laboratory of Space Weather, National Space Science Center Chinese Academy of Sciences Beijing China; School of Physics and Astronomy University of Minnesota, Twin Cities Minneapolis Minnesota USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Dai
authors.affiliation: State Key Laboratory of Space Weather, National Space Science Center Chinese Academy of Sciences Beijing China.
authors.forename: Chi
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Space Weather, National Space Science Center Chinese Academy of Sciences Beijing China.
authors.forename: Suping
authors.identifier: 0000-0002-4835-6888
authors.initials: S
authors.lastname: Duan
authors.affiliation: State Key Laboratory of Space Weather, National Space Science Center Chinese Academy of Sciences Beijing China.
authors.forename: Zhaohai
authors.initials: Z
authors.lastname: He
authors.affiliation: School of Physics and Astronomy University of Minnesota, Twin Cities Minneapolis Minnesota USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Wygant
authors.affiliation: School of Physics and Astronomy University of Minnesota, Twin Cities Minneapolis Minnesota USA.
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Cattell
authors.affiliation: Department of Geophysics and Planetary Sciences University of Science and Technology of China Hefei China.
authors.forename: Xin
authors.initials: X
authors.lastname: Tao
authors.affiliation: Department of Geophysics and Planetary Sciences University of Science and Technology of China Hefei China.
authors.forename: Zhenpeng
authors.identifier: 0000-0001-5577-4538
authors.initials: Z
authors.lastname: Su
authors.affiliation: Department of Physics and Astronomy University of Iowa Iowa City Iowa USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Kletzing
authors.affiliation: Laboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder Colorado USA.
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Baker
authors.affiliation: Laboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder Colorado USA.
authors.forename: Xinlin
authors.initials: X
authors.lastname: Li
authors.affiliation: Laboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder Colorado USA.
authors.forename: David
authors.identifier: 0000-0003-1191-1558
authors.initials: D
authors.lastname: Malaspina
authors.affiliation: Space Sciences Department The Aerospace Corporation Los Angeles California USA.
authors.forename: J Bernard
authors.initials: JB
authors.lastname: Blake
authors.affiliation: Space Sciences Department The Aerospace Corporation Los Angeles California USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Fennell
authors.affiliation: Space Sciences Department The Aerospace Corporation Los Angeles California USA.
authors.forename: Seth
authors.initials: S
authors.lastname: Claudepierre
authors.affiliation: Space Sciences Department The Aerospace Corporation Los Angeles California USA.
authors.forename: Drew L
authors.initials: DL
authors.lastname: Turner
authors.affiliation: Los Alamos National Laboratory Los Alamos New Mexico USA.
authors.forename: Geoffrey D
authors.identifier: 0000-0002-7985-8098
authors.initials: GD
authors.lastname: Reeves
authors.affiliation: Los Alamos National Laboratory Los Alamos New Mexico USA.
authors.forename: Herbert O
authors.initials: HO
authors.lastname: Funsten
authors.affiliation: Department of Physics Institute for Earth, Oceans and Space University of New Hampshire Durham New Hampshire USA.
authors.forename: Harlan E
authors.initials: HE
authors.lastname: Spence
authors.affiliation: Department of Earth, Planetary and Space Sciences and Institute of Geophysics and Planetary Physics University of California Los Angeles California USA.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Angelopoulos
authors.affiliation: Institute of Geophysics and extraterrestrial Physics Braunschweig University of Technology Braunschweig Germany.
authors.forename: Dennis
authors.identifier: 0000-0003-0092-8979
authors.initials: D
authors.lastname: Fruehauff
authors.affiliation: Department of Physics University Of Texas at Dallas Richardson Texas USA.
authors.forename: Lunjin
authors.initials: L
authors.lastname: Chen
authors.affiliation: School of Physics and Astronomy University of Minnesota, Twin Cities Minneapolis Minnesota USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Thaller
authors.affiliation: School of Physics and Astronomy University of Minnesota, Twin Cities Minneapolis Minnesota USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Breneman
authors.affiliation: School of Physics and Astronomy University of Minnesota, Twin Cities Minneapolis Minnesota USA.
authors.forename: Xiangwei
authors.initials: X
authors.lastname: Tang
keywords: electric fields; radiation belt electrons; substorm dipolarization; substorm injection