Conjugacy of ELF emission spectra and powers

• Main Authors: Sato, Masahiko, Maezawa, Kiyoshi, Fukunishi, Hiroshi, Sato, Natsuo
• Language: English
• Published: 1983
• Subjects: Husafell; Syowa Station; Antarc*; Antarctica; Iceland; Memoirs of National Institute of Polar Research; Polar Research
• Online Access: https://nipr.repo.nii.ac.jp/record/1412/files/KJ00000012046.pdf

P(論文) Conjugate observations of ELF emissions were carried out at Syowa Station in Antarctica and Husafell in Iceland from July 29 to September 18,1977. The conjugacy of ELF emissions depends on the emission types and local time. The intensity of auroral chorus is always much stronger at Husafell than at Syowa. Frequency-time (f-t) spectral patterns of polar chorus emissions depend on local time at conjugate-pair stations. In the morning sector (06-09 MLT) the lower frequency band at Syowa is stronger than that at Husafell. The conjugacy of emission patterns in f-t spectra is more complex in the daytime sector (09-14MLT), but the following tendencies are found : i) Differences in the center frequency of each event at the conjugate stations are less than 0.2kHz in the interval of 09-11 MLT, and in the interval of 11-14 MLT these become larger up to 0.5kHz. ii) The power of emissions in the frequency range higher than 0.8kHz at Husafell is about 10 dB stronger than that at Syowa. iii) Higher cutoff frequency of polar chorus is about 1kHz at Syowa, while that at Husafell extends over 1.5kHz. Statistically, polar chorus emissions are more often observed at Husafell in the whole local time. Furthermore, occurrences of polar chorus at the conjugate stations depend on geomagnetic activity. When geomagnetic activity is quiet (Kp≤1) emissions are often observed at Syowa, but emissions are more often observed at Husafell in the moderate and disturbed periods (Kp≥2). departmental bulletin paper