High resolution observations of the November 1975 decametric solar noise storm

An intense decametric solar noise storm was recorded during the third week of November 1975 with the help of a high resolution spectroscope. A large crossed Yagi antenna array was employed in conjunction with a polarization switch so as to enable spectral observations of even weak solar activity in R and L polarizations. During this storm a wide variety of bursts, such as split pairs, drift pairs, chains, hooks, dots, etc. were observed. The polarization properties of these bursts are described. In particular, microscopic spectral features like 'inverted U', 'U', 'dots' have been ascribed to the process of induced scattering of plasma waves on the thermal ions. These bursts may originate in extremely small interaction lengths (approximately 104 km) owing to the variations in the sign of local electron density gradients. Evidence is also presented for the group path delay effects on the burst profiles. (author)