On the statistical nature of type I bursts

Noise storm records obtained at Oslo Solar Observatory in the bands of 150-175 MHz and 310-340 MHz are analyzed for statistical evidence of echoes occurrence of type I bursts and the frequency distribution of events containing different numbers of bursts. Since no evidence of echoes is found, it is suggested that type I bursts are generated at a frequency which is close to the plasma frequency at the level of origin. The frequency distribution of events is shown to follow an exponential function, thereby judging that the occurrence of groups of bursts is due to chance and that the emission of type I bursts in the earth's direction is a random process. A second interpretation assumes that low frequency wave trains of random lengths are part of the burst generation mechanism. However, single bursts and chains of bursts must be explained by the same mechanism and show the same properties.