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| Author: | Charles R. Wilson |
| Institution: | 903 Koyukuk Drive, Fairbanks, AK 99775 |
| Email: | crw@gi.alaska.edu |
| Authors: | Charles R. Wilson and John V. Olson |
Abstract Title:
"Auroral Infrasound Observed at I53US at Fairbanks, Alaska" |
Abstract:
Two different types of auroral infrasound, in the passband from 0.015 to 0.10 Hz, will be described as observed at Fairbanks, Alaska. Infrasonic signals associated with magnetic storm and auroral activities have been observed in Alaska over the past 30 years. The installation of the new CTBT/IMS infrasonic array I53US at Fairbanks has resulted in a greatly increased quality of the infrasonic data with which to study natural sources of infrasound.
In the historic data at Fairbanks from 1965 to 1985 all the auroral infrasonic wave signals that were detected were found to be bow waves (AIW) that are generated by the supersonic motion of auroral arcs that contained strong electrojet currents. This AIW infrasound is highly anisotropic propagating as bow waves moving in the same direction as that of the auroral source arc. AIW bow waves observed in 2003 at I53US will be described.
Recently at I53US we have observed many auroral infrasonic events (P-AIW) of very high trace velocity continuous wavetrains of highly coherent signals that occur in the morning hours at Fairbanks at times of strong auroral activity. This new type of very high trace velocity P-AIWs appears to be associated with pulsating aurora displays. Pulsating auroras occur predominantly after magnetic midnight, (10:00 UT at Fairbanks). They are a usual part of the recovery phase of auroral substorm. They are produced by energetic electrons precipitating into the atmospheres. Given proper dark cloudless sky conditions during these high trace velocity P-AIW events, bright pulsating auroral forms were some times visible overhead.
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| Keywords: | auroral infrasound |
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