Observation and Analysis of the type Ⅲ Solar Radio Burst at Metric Wavelengths

The relation betw een the type Ⅲ bursts and the optical activities Observ ed with the High-Resolution Spectrograph at Yunnan Observ atory during the 22nd solar maximal years is statistically analysed in this article. It is found that the co rrelation betw een the Hα flares and the type Ⅲ bursts within the frequencies from 230 to 300 MHz is 70%, and over 80% of the type Ⅲ bursts have correlation to the bipolar magnetic structure and complex sunspot active regions. Therefore, it can be seen that the production of the type Ⅲ bursts has closed correlation to the bipolar magnetic structure and the complex sunspot active region. From the statistics one can see that Hαflares always result in the type Ⅲ bursts, however some type Ⅲ bursts have no relation to the Hαflares. 20% of the type Ⅲ bursts and the spike events are emerged altog ether, and principally at the lower frequency end the spike events are appeared, which develop into the type Ⅲ bursts with the increase in the frequency. Because the type Ⅲ bursts are mainly caused by the sub-relativistic electron beams, the spike events possibly have relation to the electron beams with very high energy, which is in accordance with the coexistence of the tpy eⅢ bursts and spike events.