Observation of travelling interplanetary disturbances

Abstract

A travelling interplanetary disturbance (IPD) was detected by the four station interplanetary scintillation (IPS) system of the Nagoya University on October 21, 1995 which has good time agreement with an energetic proton flare on the Sun (<20 Mev) on October 20, associated with AR 7912. The estimated shock speed of the accompanying metric type II burst, by ground radio observatories, agrees well with that measured by the IPS system. Hence, it appears that coronal type II shocks may be propagating in the interplanetary medium at least in some cases. This is in contrast to the recent statement in the literature, that 'metric type II bursts may not be considered as predictors of interplanetary shocks' (Gopalswamy et al., 1998). The event under discussion indicates that their general suggestion may not be universally appropriate in all cases.