Investigation on source locations of interplanetary type II radio bursts using radio direction finding

Source locations of interplanetary (IP) type II radio bursts can be studied by comparing radio source directions obtained using direction finding (DF) techniques with the white-light images of the associated coronal mass ejections (CMEs). Previously this method has been used to confirm that a CME-CME interaction event is the source of the concurrently observed type II enhancement. These IP type II enhancements are well suited for DF studies, because the signal-to-noise ratio of the radio emission is sufficiently high. Regular IP type II bursts are often fainter, especially so during solar cycle 24, which is characterized by a lower solar activity level and a smaller number of intense solar eruptions compared to solar cycle 23. In addition, it is known that radio wave scattering affects the DF source directions at lower frequencies. We report on our investigation on locating the radio source of regular IP type II radio bursts by comparing the DF source directions with the white-light images of the associated CMEs.