Characteristics of long and short term variations of the Jovian synchrotron radiation at a frequency of 327 MHz

The Jovian Synchrotron Radiation (JSR) is a radio wave emitted from the relativistic electrons in the Jovian radiation belt, which has information of dynamics of high-energy particles and electromagnetic disturbances in the Jovian inner magnetosphere. JSR indicates long-term (11 year) and short-term (day to weeks) variation. The short-term variation is not studied well because of the lack of continuous observation, while the long-term variation is well studied. Then we have observed JSR for several months a year since 1994 to reveal characteristics of the flux variations especially at short-term and long-term time variations. The regular observations have been made at a frequency of 327 MHz by using parabolic cylinder antennas of the Solar Terrestrial Environment Laboratory (STEL), Nagoya University. The observed JSR flux includes apparent variation due to inevitable system gain variation of the radio receiving system. In order to compensate the system gain variation, we have evaluated system gain using a flux reference radio source that was observed quasi-simultaneously with Jupiter, and made additional observations of 'actual' galactic Back-Ground radiation (BG) with the highly stable radio receiving system of Tohoku University. As the result, we derived the JSR flux densities for 1994-2003 successfully and confirmed significant flux variations in both short and long time scales. In this paper, we report the results of the JSR observations for 1994-2003 and infer causalities of the variations based on correlation analyses between the JSR flax variations and parameters of the solar activity and solar wind.
資料番号: AA0063350055