Transport of the Interplanetary Fluctuations to the Magnetopause

Fluctuations in solar wind velocity and magnetic field or relatively large amplitude on a time scale of the order of minutes are presented in interplanetary space essentially all the time.These fluctuations are transported to the region immediately outside the boundary surface of the magnetosphere.They may play an important role in the interaction of the magnetosheath plasma with the magnetopause.The interplanetary fluctuations first make a jump across the earth's bow shock.After the jump,some fluctuations are carried to reach the boundary surface of the magnetosphere.The amplitude of fluctuations at the surface of the magnetosphere is considerably amplified as compared with the interplanetary fluctuations.The solar wind conditions upstream of the bow shock control over the amplification factor This simulation study suggests that large Alfvenic fluctuations are presented at the boundary surface of the magnetosphere if the upstream fluctuations are large.The amplification factor becomes very large when the upstream magnetic field is nearly perpendicular to the sun-earth line and the amplification factor also increases with incressing plasma beta value and/or increasing Alfvenic Mach number.The effect of the state of upstream anisotropy on the amplification factor is relatively small.The present of large fluctuations indicates that no steady laminar flow exists in the boundary layer of the magnetosphere.