Occurrences of VLF Hiss and Saucer Emissins in the Southern Polar Region (c. Wave-Particle Interactions in the Magnetosphere) (Proceedings of the Second Symposium on Coordinated Observations of the Ionosphere and Magnetosphere in the Polar Regions : Part I)

• Main Authors: Takeo YOSHINO, Hiroshi FUKUNISHI, Natsuo SATO, Takayuki OZAKI, Masayuki IWASE
• Format: Article in Journal/Newspaper
• Language: English; Japanese
• Published: National Institute of Polar Research 1980
• Subjects: Geography (General); G1-922; Antarctic; Austral; Syowa Station; Antarc*
• Online Access: https://doi.org/10.15094/00008125; https://doaj.org/article/976d01040080478ca7a2433b48da8f32

Satellite data acquisition facilities for ISIS-1 and 2 were built up at Syowa Station in January 1976, and the VLF wideband and topside sounder data have been received on the routine basis since April 1976. The occurrence regions of VLF hiss and saucer emissions in the southern polar region were studied statistically by using the ISIS-1 VLF data of the 110 orbits and the ISIS-2 VLF data of the 155 orbits which were received by the 17th and 18th Japanese Antarctic Research Expedition wintering parties in 1976 and 1977. It is found that the hiss emission region with the occurrence probability larger than 50% is located at 75°–85° geomagnetic latitude in 10–14 MLT in the dayside and at 65°–80° geomagnetic latitude in 20–02 MLT in the night side, while the saucer emission region with the occurrence probability larger than 30% is located at 75°–85° in 10–18 MLT in the dayside and at 60°–70° in 18-02 MLT in the night side. It is suggested that the hiss and saucer emission regions in the dayside are closely related to field-aligned currents in the cusp region. It is also found that the altitude of the saucer emission region shows a clear seasonal variation, i e., saucer emissions are observed in the altitude range of 500–4000 km with a maximum occurrence at 2500–3000 km in the austral winter season (April-September), while they are observed at the altitude higher than 3000 km in the summer season.