Relation Between Cosmic-Ray Diurnal Variation and Type IV Solar Radio Outburst

抄録

Diurnal variation of cosmic ray intensity is often enhanced during cosmic ray storm. So it may be supposed that the diurnal variation is caused directly by some matter emitted from the sun at the time of Type IV solar radio outburst. The frequency distributions of amplitude of diurnal variations classified in many cases are obtained, and it is concluded that a part of diurnal variations has more direct relation to Tpye IV outburst than with solar flare, cosmic ray storm or geomagnetic disturbance. Furthermore, the time variation of the frequency distribution is compared with those of different quantities on cosmic rays, Type IV outburst or the others. The amplitude of diurnal variation seems to depend on the condition in interplanetary space where modulation mechanism is triggered by the matter emitted from the solar disk at the outbreak of Type IV outburst.