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IMAGE and FAST observations of substorm recovery phase aurora
Author(s) -
Mende Stephen B.,
Frey Harald U.,
Carlson Charles W.,
McFadden J.,
Gérard JeanClaude,
Hubert Benoit,
Fuselier Stephen A.,
Gladstone G. R.,
Burch James L.
Publication year - 2002
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 - 10.1029/2001gl013027
Subject(s) - substorm , physics , electron precipitation , flux (metallurgy) , electron , latitude , proton , geophysics , geology , astrophysics , magnetosphere , magnetic field , astronomy , materials science , quantum mechanics , metallurgy
Images from the IMAGE Wide‐band Imaging Camera (WIC) and Spectrographic Imager (SI) channel SI12, were compared to in situ data taken by FAST. The IMAGE data segment began during the expansive phase of a substorm and a double oval configuration evolved, consisting of a set of discrete poleward auroral forms and a separate more diffuse oval. The FAST data showed that a narrow (∼1.5° latitude) region of downward currents separated the two ovals. The SI‐12 optical observations showed a single oval of precipitating protons located on the equatorward side within the diffuse aurora. In agreement with IMAGE, the highest intensity proton flux measured by FAST was concentrated on the equatorward region although low flux protons were present throughout the entire double oval. In the lower latitude diffuse oval occasional structured auroras were embedded. These structured auroras were mostly created by inverted V type electrons but there were narrow regions in which intense beams of accelerated electrons were seen whose energy/pitch angle distribution and accompanying electric field data were consistent with Alfven wave acceleration. The poleward oval consisted of an intense inverted V precipitation event poleward of which a weak region of Alfven wave accelerated electrons was located. From the images it appears that the Alfven wave accelerated electron event in the diffuse auroral regions and the poleward features were part of short lived or rapidly moving auroral forms.