Numerical investigation of the homologous coronal mass ejection events from active region 9236

We present a three-dimensional compressible magneto-hydrodynamics (MHD) simulation of the three coronal mass ejections (CMEs) of 2000 November 24, originating from NOAA active region 9236. These three ejections, with velocities around 1200 km s-1 and associated with X-class flares, erupted from the Sun in a period of about 16.5 hr. In our simulation, the coronal magnetic field is reconstructed from MDI magnetogram data, the steady-state solar wind is based on a varying polytropic index model, and the ejections are initiated using out-of-equilibrium semicylindrical flux ropes with a size smaller than the active region. The simulations are carried out with the Space Weather Modeling Framework. We are able to reproduce the shape and velocity of the CMEs as observed by the LASCO C3 coronograph. The complex ejecta resulting from the interaction of the three CMEs is preceded at Earth by a single shock wave, which, in our simulation, arrives at Earth 10 hr later than the shock observed by the Wind spacecraft. This article discusses the three-dimensional aspects of the propagation, interaction, and merging of the forward shock waves associated with the three ejections. Synthetic images from the Heliospheric Imagers onboard the STEREO spacecraft are produced, and we predict that the large density jump associated with the interaction of the shocks should be observed by those coronographs in the near future