Propagation of Interplanetary Shocks in the Inner Heliosphere

Abstract Interplanetary (IP) shocks are one of the crucial dynamic phenomena in the heliosphere. They can accelerate particles to high energies, generate plasma waves, and trigger geomagnetic storms in Earth’s magnetosphere, significantly impacting technological infrastructure. In this study, two IP shock events are selected to study the temporal variations of the shock parameters using magnetometer and ion plasma measurements from STEREO-A and B, the Wind, Cluster fleet, and the Advanced Composition Explorer spacecraft. The shock normal vectors are determined using minimum variance analysis and magnetic coplanarity methods. During the 2007 May 7 event, the shock parameters and the shock normal direction remain consistent across each spacecraft crossing of the shock. The shock surface appears to be tilted by almost the same degree as the Parker spiral, and the driver could be a corotating interaction region (CIR). During the 2007 April 23 event, the shock parameters do not change significantly except for the shock angle θ Bn ; however, the shape of the IP shock appears to be twisted in the direction perpendicular to the Sun–Earth line as well. The driver of this rippled shock is a stream interaction region/CIR as well.