Abstract

We compare radio dynamic spectra with images in soft X-rays, 17 GHz microwave, and Hα, for three solar flares. We find that negative drifts of cutoff frequencies in a series of radio decimetric bursts observed in the radio dynamic spectra correspond to plasma cloud ejections seen in the images. By relating the radio frequency drift-rate to a global morphological change in the flare region, namely, a loop expansion caused by plasma cloud ejection, we discuss where the decimetric bursts are produced, in conjunction with a possible flare scenario.