The solar cause of interplanetary disturbances observed in the distance range 0.24–1 AU

Abstract

Interplanetary disturbances are an important aspect of the physics of the sun and heliosphere. They are identified as an increase in the density turbulence compared with the ambient solar wind. Here, we report the detection of a large number of interplanetary disturbances within the distance range 0.25–1 AU based on interplanetary scintillation measurements made between 1986 and 1991. For the first time, this yields the helio‐latitudinal distribution of interplanetary transients at different phases of the solar cycle, thereby providing insight into the physical processes influencing these phenomena. It is found that near solar minimum (1986–mid–1988), transients originate in the equatorial region of the Sun. As solar activity increases, they are observed at higher latitudes, and even in the polar regions at solar maximum (1989–1991). These disturbances also show a wide range of speeds, with a global average speed of ∼450 kms−1. More than 80% of the disturbances are associated with the active prominences on the Sun, which are suggested to be the source of coronal mass ejections.