Radio Observation Data at syowa Station

 当所では、南極昭和基地にて1966年2月から2007年1月まで、RIOメータ(Rerative Ionosphere Opacity meter)30MHz等で宇宙電波雑音吸収の観測を実施しました。





The riometer receiver has a center frequency of 30 MHz and a band width of 7.5 kHz and is connected to a vertically directed five-element Yagi antenna whose elements are oriented in the east-west direction. The antenna is designed to match the 50-ohm coaxial cable (10D-2E), which is 100 m long. Noise signal from a reference noise diode, with power levels of 4000, 8000, 12000, 16000, and 20000 K, is inserted each day at 0800 of 45°eastern meridian time (EMT: UT + 3 hours). The output signal of riometer is converted analog to digital every second and stored in a digital storage system.

The cosmic noise power level shows a remarkable sidereal diurnal variation caused by the passage of the cosmic radio source across the zenith. Due to the earth's revolution, the time of the zenith passage of a particular cosmic radio source occurs approximately four minutes earlier each day and returns to its initial time after one year. This diurnal variation of the cosmic noise power is deduced from the record on the quiet days.

The ionospheric absorption in dB is obtained as follows:

  1. The reference sidereal diurnal variation of the cosmic noise power,T0 , given in K is determined from the diurnal variations on several selected quiet days each month.
  2. Actual received power,T1, is given in K.
  3. Ionospheric absorption A, given in dB, is calculated with the following conversion equation:

The combined data plots include the variation of the H-component of the geomagnetic field at Syowa Station.


2000年 2001年 2002年 2003年
2004年 2005年 2006年 2007年