Detailed comparison of type III radio bursts with Hα activity

Abstract

Isolated type III radio burst activity was observed at Clark Lake Radio Observatory in March and the first part of April, 1971, to occur in discrete regions of the corona above certain active regions. When these regions were examined under high resolution in Hα all the type III events appeared to have associated activity in Hα. The potential coronal magnetic field in these regions appeared to be either open or diverging, whereas the field over a rather active region which did not have radio burst activity was closed in a magnetic arcade. The latter feature has been associated with streamers. Streamers have also been associated with dark filaments. The occurrence of a stable dark filament in an active region appeared to have an inhibiting effect on type III activity. It is suggested that a streamer field configuration is not favorable to the escape of isolated type III exciters.