Multipoint Analysis of the Interaction between a Shock and an ICME-like Structure around 2011 March 22

Abstract

This work reports on the interaction between a fast forward shock and an interplanetary coronal-mass-ejection-like structure (ICMELS) as observed by in situ observations of radially aligned spacecraft. Around 2011 March 22, the Venus EXpress (VEX) and Solar TErrestrial RElations Observatory-A (STEREO-A) were nearly at the same longitude, providing us with an excellent opportunity to study the formation and evolution of the complex structures. The shock and ICMELS investigated in this paper are isolated near Venus, but when they approach STEREO-A, the shock nearly approaches the front edge of the ICMELS and forms a shock–ICMELS complex structure. The maximal magnetic field in the ICMELS increased 2.3 times due to shock compression, according to the observation. The recovery model, which restores the shocked portion of the shock–ICMELS to its uncompressed condition, likewise confirms this improvement. The interaction with the ICMELS, on the other hand, weakens shock 2. The magnetic compression ratio falls from 2.4 at Venus to 2.0 at STEREO-A. This research enables us to have a better physical knowledge of the impacts of the interaction between a shock and an ICME (or ICMELS), which will aid future space weather predictions.