Auroral Infrasonic Waves

The morphology of auroral infrasonic waves at College, Alaska, is related to the temporal and spatial distributions of supersonic auroral motions that develop within the auroral oval during polar magnetic substorms. The break-up phase of the auroral substorm results in the rapid auroral motions that generate the observed infrasonic waves. Direct observations of infrasonic wave packets from overhead supersonic auroral forms, as well as the comparison of the morphologies of infrasonic waves and auroral motions are used to verify a shock wave model for the generation of auroral infrasonic waves. Electrodynamic drift and joule heating associated with the auroral electrojets in auroras that produce infrasonic shock waves are accepted as the basic processes that generate the initial acoustic pulse within a moving auroral form.

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