Open Access

MHD wave characteristics inferred from correlations between X-rays, VLF, and ULFs at Syowa Station, Antarctica and Tjörnes, Iceland (L6)

  • Yo Hirasima1Email author,
  • Hisashi Shimobayashi1,
  • Hisao Yamagishi2,
  • Hiromu Suzuki1,
  • Hiroyuki Murakami1,
  • Akihiro Yamada1,
  • Takamasa Yamagami3,
  • Michiyoshi Namiki3 and
  • Masahiro Kodama4
Earth, Planets and Space201451:BF03352207

Received: 18 March 1997

Accepted: 8 October 1998

Published: 6 June 2014


The Polar Patrol Balloon No. 6 (PPB#6) observed quasi-periodic pulsations of bremsstrahlung X-rays (E 30120 keV) in the daytime of 0855 UT (0914 MLT) 1630 UT (1614 MLT) on January 5, 1993, near Syowa Station, Antarctica (L6). The X-ray pulsations near the noon (1208:00 UT (1216 MLT) 1225:04 UT (1232 MLT)) include a period of about 260 sec, which corresponds to Pc 5 magnetic pulsations. It was found that at Syowa Station and Tjörnes, Iceland, which are both pair locations of the geomagnetic conjugacy, the X-ray pulsations are in correlation with the ULF-D pulsations. Also the Tjörnes VLF (2 kHz) pulsations correlated well with the X-ray pulsations of the period corresponding to Pc 5. It is probable that the VLF- and ULF-associated X-rays or precipitating energetic electrons in the vicinity of the L 6 shell are in synchronization with the electron-cyclotron resonance. Lastly, the so-called ballooning-mirror instability (the BMI) is a candidate to explain the compressional MHD waves that occur during the short time interval (1216 MLT 1232 MLT) in which the experimental results were interpreted.


Energetic ElectronMagnetic PulsationGeomagnetic PulsationMagnetic Local TimeWhistler Mode