PERIODIC OSCILLATION IN SOLAR RADIO EMISSION PRECEDING MICROWAVE BURST

In this paper we have analysed the burst data at 3.2cm and 10cm during the period January to December,1979.The bursts that the peak flux density increase-ment (S/S)≥50% amount to 25 and we find that there are oscillations on the preburst recording curves of all the 25 bursts,the period of the oscillation is from a few seconds to ten seconds and the amplitude is about 1% of the solar undisturbed component.Such a oscillation usually precede burst for a few hours or a few days,but for outstanding burst it will be disappeared for tens minuts or a few hours before burst,and without this phenomenon in smaller,impulsive and shorter complex bursts.Thus the oscillating characteristics may be a process of energy accumulation in flare region.