Dipole tilt control of the magnetopause for southward IMF from global magnetohydrodynamic simulations

Abstract

[1] Numerical results from a physics-based global magnetohydrodynamic (MHD) model are used to examine the effect of the dipole tilt angle (y) on the location and shape of the magnetopause. Identification of the magnetopause location in the simulation domain is automated using criteria based on the current density and the shape of the streamlines. These data are fitted with a three-dimensional surface controlled by 10 configuration parameters which allow description of the cusp geometry as well as the asymmetry in the Z direction and the azimuthal asymmetry of the magnetopause. Effects of dipole tilt angle on the configuration parameters are analyzed from a series of simulations for southward IMF and different dipole tilt angle values. It is found that dipole tilt angle has little impact on the equatorial magnetopause but significantly affects the cusp locations and the degree of asymmetry between the Northern and Southern hemispheres and the equatorial/ meridional plane. The results are shown to be consistent with three frequently used empirical models derived from satellite observations.

Effects of the interplanetary magnetic field on the twisting of the magnetotail: Global MHD results

“…By finding approximately the solar wind streamlines encompassing the inner edge of the void, Palmroth et al [2003] developed an automated technique for identifying the magnetopause surface from the simulations. Recently, Liu et al [2012] indicated that the streamline method is not able to determine the subsolar point very well, and they used the peaks of the current density to identify the subsolar magnetopause instead. In this study, we make a slight modification of the streamline method as Liu et al [2012] did.…”

“…Recently, Liu et al [2012] indicated that the streamline method is not able to determine the subsolar point very well, and they used the peaks of the current density to identify the subsolar magnetopause instead. In this study, we make a slight modification of the streamline method as Liu et al [2012] did.…”

“…Hasegawa et al [2002aHasegawa et al [ , 2002b studied IMF dependence of the distant tail shape using the plasma and magnetic field measurement and found that the yz cross section of magnetotail stretches along IMF direction. Recently, using the MHD simulations, Lu et al [2013] improved the three-dimensional model on the basis of Liu et al [2012] to investigate the influence of IMF B y and B z on the shape of magnetopause. They found that the stretch direction of the magnetopause cross section is always near the direction of the IMF but is a little closer to the meridional plane than the IMF.…”

The dayside magnetopause location during radial interplanetary magnetic field periods: Cluster observation and model comparison

“…Previous work has shown that the solar wind dynamic pressure can affect the magnetopause size, while the shape of the magnetopause is controlled by the IMF B z (e.g., Shue et al, 1997;Lu et al, 2011;Boardsen et al, 2000). Later work has further indicated that the dipole tilt angle can also affect the magnetopause shape (e.g., Liu et al, 2012). Our work has indicated that the IMF cone angle might be another important parameter that can affect the magnetopause shape.…”

“…The latter fact indicates that the dipole tilt effect is not fully represented by the Boardsen00 model. Previous work has shown that the dipole tilt angle has few effects on the equatorial magnetopause but has great effects on the high-latitude magnetopause (Lin et al, 2010;Liu et al, 2012;Boardsen et al, 2000). As the dipole tilt angle becomes more negative, the high-latitude magnetopause is displaced inwards in the Northern Hemisphere, while in the Southern Hemisphere the magnetopause is displaced outward (Boardsen et al, 2000).…”