The dipole tilt angle dependence of the bow shock for southward IMF: MHD results

摘要

The location and shape of the Earth's bow shock depend on the properties of the upstream solar wind, as well as the size and shape of the downstream magnetopause. Many studies have suggested that the influence of the dipole tilt angle on the magnetopause is significant, especially at the high-latitude region, however, to date there is no bow shock model which depends on the dipole tilt angle. Using a physics-based global magnetohydrodynamic (MHD) model, the Space Weather Modeling Framework (SWMF), we investigate the effect of the dipole tilt angle on the location and shape of the bow shock, and our results show that (1) the subsolar standoff distance and the north-south asymmetry of bow shock increase with the increasing dipole tilt angle; (2) with the dipole tilt angle positively increasing, the flaring angle of the bow shock increases in the northern hemisphere but keeps almost unchanged in the southern hemisphere, and the rotational asymmetry slightly decreases in the northern hemisphere and rapidly decreases in the southern hemisphere; and (3) the influence of dipole tilt angle on the shape of the bow shock is north-south symmetric. (C) 2014 Elsevier Ltd. All rights reserved.