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Direct auroral precipitation from the magnetotail during substorms
Author(s) -
AshourAbdalla Maha,
Schriver David,
Alaoui Mostafa El,
Richard Robert,
Walker Raymond,
Goldstein Melvyn L.,
Donovan Eric,
Zhou Meng
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50635
Subject(s) - substorm , electron precipitation , electron , physics , precipitation , earth's magnetic field , geophysics , atmospheric sciences , pitch angle , magnetosphere , computational physics , magnetic field , meteorology , quantum mechanics
In this study, we examine the causes of electron precipitation during a substorm on 15 February 2008 that lead to auroral brightening. We use global kinetic simulations along with spacecraft and ground‐based data. We find ~keV electrons in the region modeled in the simulation precipitate into the premidnight sector at latitudes between 71° and 75° due to two distinct physical processes: (1) higher latitude precipitation due to electrons that undergo relatively rapid non‐adiabatic pitch angle scattering into the loss cone just earthward of a reconnection region, and (2) lower latitude precipitation due to electrons that are more gradually accelerated primarily parallel to the geomagnetic field by Fermi acceleration. These latter electrons enter the loss cone much closer to Earth at ~−15 to −10 R E . The electron precipitation due to the combination of these two mechanisms coincides spatially with observed auroral brightening during the disturbed event.