  In recent studies (Feng et al., 2012; Kong et al., 2012), we proposed that
source properties of type II radio bursts can be inferred through a causal
relationship between the special shape of the type II dynamic spectrum (e.g.,
bump or break) and simultaneous extreme ultraviolet (EUV)/white light imaging
observations (e.g., CME-shock crossing streamer structures). As a further
extension of these studies, in this paper we examine the CME event dated on
December 31 2007 associated with a multiple type II radio burst. We identify
the presence of two spectral bump features on the observed dynamic spectrum. By
combining observational analyses of the radio spectral observations and the
EUV-white light imaging data, we conclude that the two spectral bumps are
resulted from CME-shock propagating across dense streamers on the southern and
northern sides of the CME, respectively. It is inferred that the corresponding
two type II emissions originate separately from the two CME-shock flanks where
the shock geometries are likely quasi-perpendicular or oblique. Since the
emission lanes are bumped as a whole within a relatively short time, it
suggests that the type IIs with bumps of the study are emitted from spatially
confined sources (with a projected lateral dimension smaller than 0.05-0.1
R$_\odot$ at a fundamental frequency level of 20-30 MHz).

Solar and Stellar Astrophysics