The impact on global magnetohydrodynamic simulations from varying initialisation methods: results from GUMICS-4

摘要

We investigate the effects of different initialisation methods of the GUMICS-4 global magnetohydrodynamic (MHD) simulation to the dynamics in different parts of the Earth's magnetosphere and hence compare five 12a?ˉh simulation runs that were initiated by 3a?ˉh of synthetic data and followed by 9a?ˉh of solar wind measurements using the OMNI data as input. As a reference, we use a simulation run that includes nearly 60a?ˉh of OMNI data as input prior to the 9a?ˉh interval examined with different initialisations. The selected interval is a high-speed stream event during a 10-day interval (12a??22??June??2007). The synthetic initialisations include stepwise, linear and sinusoidal functions of the interplanetary magnetic field with constant density and velocity values. The results show that the solutions converge within 1a?ˉh to give a good agreement in both the bow shock and the magnetopause position. However, the different initialisation methods lead to local differences which should be taken into consideration when comparing model results to satellite measurements.