Propagation of solar disturbances and heliospheric storms

Abstract

In this paper, we review solar disturbances (solar flares) and their propagation towards the earth and to the heliosphere. For solar flares, we consider that a photospheric dynamo supplies the power and that high speed streams are caused by the basic solar wind (modified by the solar magnetic field), not from coronal holes. These new views allow us to predict the occurrence of solar flares and the 27-day recurrent storms more accurately than in the past. It is suggested that the explosive aspect of solar flares, the phenomenon, called ‘diparition brusques (DB)’, is the source of coronal mass ejections (CMEs)/magnetic clouds (MCs) and of heliospheric disturbances, namely heliospheric storms. It is also suggested that some CMEs have a magnetically helical structure, which are rooted at the sun. For the inner heliospheric storms, a simple method, called the HAF method, is used to study the propagation of solar disturbances and tested by various simultaneous space probes, such as IMP, HELIOS A, and B for the inner heliosphere. For the middle heliosphere, the same method is tested at a distance 7 au with the Pioneer 11 data; the result is satisfactory. The method is further extended to 100 au in an early 2004; thus, it is possible to envisage the whole heliospheric disturbances over 200 days.