| Summary: | P(論文) Experimental results obtained by the sounding rockets at Syowa Station, Antarctica, are briefly summarized. The electron density profiles in auroras were measured by the rockets which penetrated into intensely bright (∿30kR for OI 5577 Å), bright (∿10kR) and weak (∿5kR) auroras. The E-region electron density amounts to ∿1.2×(10)^6 el/(cm)^3,∿5.0×(10)^5 el/(cm)^3 and ∿6.0×(10)^4el/(cm)^3 for intensely bright, bright and weak auroras respectively, while it is ∿6.0×(10)^3el/(cm)^3 for no aurora during the night. The electron density in the D-region beneath the lower boundary of an intensely bright arc (75-98 m in altitude) is also considerably enhanced, up to 0.7-1.0×(10)^6 el/(cm)^3. In bright auroral arcs, the electric field becomes small and points in the equatorward direction, whereas it becomes large with the predominant westward direction in the near space outside of a bright auroral arc. The electric field fluctuations (up to 240Hz in frequency) are greatly enhanced in auroras over a wide frequency range, at altitudes of 100-120km. Various kinds of VLF and HF emissions are observed in the auroral ionosphere. Characteristics of these emissions and their relations to the precipitating electron flux are discussed. departmental bulletin paper
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