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ELF/VLF emission observation by Polar Patrol Balloons

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Abstract

Circum-Antarctic balloons were launched from Syowa Station by the 44th Japanese Antarctic Research Experiment team in January 2003. Two balloons equipped with identical instruments were flown in formation around the Antarctic continent, in an attempt to separate temporal and spatial variations of the auroral phenomena. In this paper, we report instrument design, operation and some initial results of the ELF/VLF wave experiment by PPB No. 8 and 10 balloons.

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Frequency-time (f-t) spectra of quasi-periodic (QP) ELF-VLF emissions in the period range 5-200 s are examined by using a few hundred QP events observed at high latitudes. These f-t spectra are classified into five types: nondispersive, rising tone, falling tone, mixed, and burst. Statistical characteristics of QP emissions in each type are examined by using f-t spectra of ELF-VLF emissions recorded continuously for 50 days in Iceland. A phenomenological model to explain the f-t spectra is proposed; that is, the rising tone type of QP emission is generated by compressional mode Pc 3 magnetic pulsations which propagate in a radial direction toward the earth, while the nondispersive type is generated by standing oscillations of the magnetic fields which have effective compressional components.
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Article
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