Solar microbursts at meter-dekameter wavelengths

Microbursts are low-brightness-temperature bursts observed by the Clark Lake radioheliograph. The bursts occur several times per hour during quiet-sun periods and are seen at the observing frequencies from 30 to 70 MHz. They are stationary at a given frequency, have short rise times and durations of 2-10 s. Here, observations of the bursts are presented and interpretated in terms of plasma emission. The burst properties suggest that they are weak type III bursts. The observations imply that energy releases on the sun continue to be impulsive, with nonthermal electron distributions, for small releases of energy. The relation of the bursts to type III bursts and hard X-ray bursts is discussed.