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

Diagnostics on the source properties of type II radio burst with spectral bumps