In:
Journal of Geophysical Research: Space Physics, American Geophysical Union (AGU), Vol. 90, No. A1 ( 1985-01), p. 457-466
Abstract:
On the evening of March 5, 1981, an intense, type A red aurora appeared over southern Alaska. Radar and photometric measurements were made of the aurora from the Chatanika radar site. The line of sight intensity of the 630.0‐nm emissions exceeded 150 kR and was accompanied by enhanced emissions at 486.1 and 427.8 nm. The Chatanika radar measured electron densities of 10 6 cm −3 and electron temperatures of 6000 K at an altitude of 400 km and an invariant latitude of 59° in association with the aurora. Comparison of optical and radar measurements indicated that the 630.0‐nm emissions were produced to a large degree by thermal excitation of O(¹ D ) in the region of high electron temperatures and densities. Model calculations indicate that the observed density and temperature enhancements and the related optical emissions were the results of a relatively short duration (5–10 min) pulse of precipitating, low‐energy (∼30 eV) electrons. Whereas conventional stable auroral red arcs are associated with a gradual decrease in ring current energy density during the recovery phase of a magnetic storm, the type A red aurora may be produced by impulsive ring current energy loss during the main phase.
Type of Medium:
Online Resource
ISSN:
0148-0227
DOI:
10.1029/JA090iA01p00457
Language:
English
Publisher:
American Geophysical Union (AGU)
Publication Date:
1985
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