Propagation of interplanetary shock waves by observations of type II solar radio bursts on IMP-6

A new interpretation of the low frequency type II solar radio bursts of 30 June 1971, and 7–8 August 1972 observed with IMP-6 satellite (Malitson et al., 1973a,b) is suggested. The analysis is carried out for two models of the electron density distribution in the interplanetary medium taking into account that N ~ 3.5 cm^?3 at a distance of 1 a.u. It is assumed that the frequency of the radio emission corresponds to the average electron density behind the shock front which exceeds the undisturbed electron density by the factor of 3. The radio data indicate essential deceleration of the shock waves during propagation from the Sun up to 1 a.u. The characteristics of the shock waves obtained from the type II bursts agree with the results of the in situ observations.