The Influence Of B_x And B_y On The Energy Transfer Across The Magnetopause

The solar wind-magnetosphere energy coupling includes two aspects:the material and energy of the solar wind entering the magnetosphere-ionosphere system and then dissipating in the system,and the material and energy escaping from the magnetosphere-ionosphere.In the process of solar wind energy injection into the magnetosphere and ionosphere,it must firstly impact on the magnetopause,so the study of the energy transfer across the magnetopause has a certain indicative effect on the energy transmission,distribution and dissipation in the coupling system,and it is undoubtedly a very important physical process and research hotspot in space weather.Based on the results of global MHD model,this paper quantitatively studies the energy transfer from the solar wind through the magnetopause to the magnetosphere under the interplanetary magnetic fields of B_x and B_y.Because the research on the magnetic reconnection and the energy transmission of the magnetopause under the condition of the north-south direction has been relatively perfect,this paper studies the energy transfer of the solar wind through the magnetopause into the magnetosphere under the conditions of B_x and B_y condition in detail.Through streamline method,the smooth magnetopause surface is determined by looking for the inner boundary of the solar wind current line containing magnetopause,and the total energy is divided into mechanical energy and electromagnetic energy.The distribution characteristics of mechanical energy and electromagnetic energy.The location of magnetic reconnection is determined by the distribution of magnetic lines under the condition of B_x and B_y calculated by numerical model to analyze the influence of magnetopause reconnection on energy transmission.Because the magnetopause reconnection is not the only reason to drive the energy transmission,and the viscous effect of the magnetotail also plays a certain contribution.Therefore,the deflection direction and degree of the magnetotail plasma flow are analyzed by the relationship between the deflection angle and the azimuth angle of the streamline near the magnetopause of YZ plane with X=-35R_E to analyze the influence of the viscous effect of the magnetotail.The physical mechanism of energy transfer at the magnetopause under the condition of B_x and B_y is analyzed.Finally,the energy transfer across the magnetopause under the north-south IMF condition is compared with that under the condition of B_x and B_y,and the energy transfer rate is analyzed.The main results are as follows:(1)Under the condition of radial solar wind,the location of magnetic reconnection is different in the northern and southern hemispheres,that is,when B_x is positive,it occurs in the front of the cusp in the northern hemisphere,and in the back of the cusp in the southern hemisphere,and when B_x is negative,the location is symmetrical about the Z=0 plane,which makes the energy asymmetry in the southern and northern hemispheres.When the IMF B_x is positive or negative,the energy distribution is symmetrical about the Z=0 plane.For the magnetotail viscosity,similar to the north direction,the magnetotail plasma flow will flow from the high latitude to the low latitude along the tangential direction,but its deflection is obviously smaller than the north direction.(2)Under the condition of IMF B_y,magnetopause deflects at a certain angle in the dawn-dusk direction,and the location of the magnetic reconnection also moves in the dawn-dusk direction.When B_y is positive reconnection takes place on the dusk side of the northern hemisphere and the dawn side of the southern hemisphere,while B_y is negative,location is symmetrical with respect to the mirror image of the Y=0 plane,which makes the energy deflect in the dawn-dusk direction in the distribution of the magnetopause,The energy distribution in the positive and negative directions of B_y is symmetric with respect to the mirror image of plane Y=0.For the magnetotail viscosity,different from the north and radial conditions,there is a certain angle deflection at the beginning of the deflection of the magnetotail plasma flow in the dawn-dusk direction,and the deflection degree is slightly larger than that in the radial condition,but still significantly smaller than that in the north direction.(3)Compared with the energy transfer across the magnetopause under the condition of the north and south IMF,it is found that 4.95%of the energy enters the magnetophere when the south direction,with the largest amount of energy injected;the energy input when B_y=±5 n T follows closely,with the transmission rates of 3.52%and 3.58%respectively;When B_x=±5n T,2.22%of the energy is injected into the magnetosphere,and the minimum energy injected into the magnetosphere is the north IMF,with a transmission rate of only 1.7%;...