Electronic Resource
Springer
Space science reviews
22 (1978), S. 77-113
ISSN:
1572-9672
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract Observations indicate that the extended auroral arc is the basic form of the discrete aurora, the brightest and most obvious kind of aurora. Both motions of auroral arcs and their distortions into convoluted forms indicate the presence of shear processes involving substantial charge excesses and magnetic field-aligned currents. Consequently, strong electric fields, both horizontal and vertical, characterize the discrete aurora. The observations of auroral arcs and observations of associated charged-particle fluxes, electric fields and currents fit together into a relatively cohesive description of the auroral arc which is compatible with at least one proposed model of the causative processes. On the other hand, an equally important type of aurora — pulsating aurora — exhibits quite different characteristics which distinguish it from the discrete aurora and which are difficult to interpret satisfactorily in terms of existing proposed models of particle precipitation and excitation of auroral emission. The lack of shearing behavior in the pulsating aurora indicates that substantial electric fields are not associated with it. Transitional forms of auroras exhibit an intermediate degree of shear motion.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00215814
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