Open AccessEnergy source for auroral electrons from two proposed substorm onset processes
Author(s) -
Lui A. T. Y.
Publication year - 2011
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2010ja016332
Subject(s) - substorm , physics , electron precipitation , electron , flux (metallurgy) , geophysics , energy flux , kinetic energy , particle acceleration , computational physics , astrophysics , magnetosphere , atomic physics , magnetic field , astronomy , nuclear physics , classical mechanics , materials science , quantum mechanics , metallurgy
There are two main processes in the tail that are proposed to link electron precipitation for the initial brightening auroral arc at substorm onset. These are current disruption/dipolarization (CDD) and magnetic reconnection (MR). To provide further clues in differentiating these two processes, we examine the electron energy spectrum and the associated total field‐aligned energy flux during six CDD events and compare them with five MR events. Data from the Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (AMPTE/CCE), Geotail, and Time History of Events and Macroscale Ineractions during Substorms (THEMIS) missions are used in this study. It is found that (1) the total field‐aligned electron energy flux from CDD sites is generally high enough to account for the energy flux required to produce bright auroral arcs at substorm onsets and (2) the total field‐aligned electron energy flux from MR sites is generally a factor of one to two orders of magnitude lower than that from CDD sites. These results favor a direct link between the CDD sites and the substorm onset arcs, but they do not rule out further acceleration of auroral electrons away from these sites by other energy sources (e.g., field‐aligned potential drops and kinetic Alfvén waves) to produce even higher‐intensity auroral arcs.