Multi-wave Band Observation of Bi-directional Type Ⅲ Drift Bursts

The 11 pairs of type Ⅲ bursts with the bi-directional drift structure recorded with the spectrograph within the frequency ranges of 230~300MHz, 625~1500MHz, 1000~2000MHz and 2600~3800MHz at Yunnan Observatory are analyzed in this article. The half-power duration, the frequency drifts rate and the degree of polarization with bi-directional type Ⅲ bursts are compared with ordinal type Ⅲ bursts, and their relations to Hα flares are analyzed. Outstanding characteristics of these events are obtained. The qualitative explanation of these events is given in this paper.