Effect of the interplanetary electric field on the magnetopause from global MHD simulations

Abstract

The north-south component <I>B</I><SUB>z</SUB> of the Interplanetary Magnetic Field (IMF) and solar wind dynamic pressure <I>P</I><SUB>d</SUB> are generally treated as the two main factors in the solar wind that determine the geometry of the magnetosphere. By using the 3D global MHD simulations, we investigate the effect of the Interplanetary Electric Field (IEF) on the size and shape of magnetopause quantitatively. Our numerical experiments confirm that the geometry of the magnetopause are mainly determined by <I>P</I><SUB>d</SUB>B</I><SUB>z</SUB>, as expected. However, the dawn-dusk IEFs have great impact on the magnetopause erosion because of the magnetic reconnection, thus affecting the size and shape of the magnetopause. Higher solar wind speed with the same <I>B</I><SUB>z</SUB> will lead to bigger dawn-dusk IEFs, which means the higher reconnection rate, and then results in more magnetic flux removal from the dayside. Consequently, the dayside magnetopause moves inward and flank magnetopause moves outward.