On the type of spectra of S-component sources and their correlation with flare occurrence

From solar maps at 8.6 mm wavelength and total flux measurements at wavelengths of 1.7 cm to 122 cm, various spectra of the slowly varying component have been studied. The main distinction between these various types of spectra is the slope of the spectra toward wavelengths of less than 2 cm.It has been shown that the probability of flare occurrence is correlated with the type of the source spectra. It is proposed that enhanced flare production occurs from a source of SVC whose spectrum has a peak around 6–10 cm wavelength but whose slope is flatter around 8 mm, but steeper toward longer centimeter wavelengths, than in the case of normal SVC-spectra attributed to gyro resonance radiation. The implications of such spectra in terms of changes in magnetic field structure before the occurrence of a flare are discussed.