Shock waves standing in the middle- and high-latitude magnetosheath from global MHD simulations

Abstract

Standing shock waves (SSWs) are found to exist in the middle-and high-latitude magnetosheath through the global magnetohydrodynamic simulations. There are two (or one) SSWs for constant northward (or southward) interplanetary magnetic field (IMF); they extend into the magnetosheath region and further interact with the bow shock. Because of the extension of SSWs into the interplanetary space, especially when IMF turns southward, an indented bow shock emerges in front of the magnetosphere. The SSWs are excited by the indentations of the magnetopause in the supermagnetosonic solar wind flows in the magnetosheath; for northward IMF, one of the indentations is located in the cusp region and the other corresponds to the neutral point in the tailward of the cusp; for southward IMF, the indentation simply locates in the cusp region. We examine the Rankine-Hugoniot relations across the shock fronts and find the numerical model results are consistent with theoretical predictions.