Frequency dependent characteristics of solar impulsive radio bursts

Abstract

Impulsive solar radio bursts are analyzed in order to study the frequency dependence of occurrences of impulsive radio bursts and of north-south and east-west asymmetries. It appears that the burst duration increases steadily with increasing frequency up to a certain frequency, from which it decreases. The more intensive Simple 2 bursts last longer than Simple 1 bursts above 2 GHz while the reverse is true below this frequency. The N-S asymmetry is frequency-dependent and more pronounced for Simple 1 bursts than Simple 2 bursts at all frequencies. Simple 1 bursts clearly prefer the southern hemisphere, while Simple 2 bursts favor the north. The E-W asymmetry is more pronounced for Simple 1 bursts than for the other type, with both types favoring the eastern hemisphere. The burst spectra are generally inverted U-type with the maximum emission intensity between 5 and 15 GHz.