Size and Shape of Magnetopause in the Noon-midnight Meridian Plane Based on the MHD Simulation

A quantitative model about the location and Shape of Magnetopause (MP) in the noon-midnight meridian plane is given by analyzing the computing data from three-dimensional global MHD simulation of the magnetosphere. Data processing results show the function which was presented by Ref.[3] based on the satellite observational data can also be used to describe MP in noon-midnight meridian plane. The location and shape of the MP in the noon-midnight meridian plane are more complicated than those in the equatorial plane. Although the MP in cusp region is ignored, the location and shape of MP need still be fitted by two different curves. The dynamic pressure of the solar wind (Dp) and the north-south component of the interplanetary magnetic field (IMF Bz) are two main factors determining the size and shape of MP. While for northward IMF Bz, r0 increases with increasing northward Bz; for southward IMF Bz, the standoff distance r0 decreases with increasing southward IMF Bz. On the whole, r0 increases when Bz turns northward from southward, and the influence of Bz on r0 becomes weaker. r0 is mainly affected by the dynamic pressure Dp, r0 decreases with Dp increasing. The other variable α, the level of tail flaring, increases with southward IMF increasing, which means the magnetopause flares more strongly and more magnetic flux transfers from the dayside to the nightside. The value of α rises slightly with Dp increasing, which implies that Dp also helps to some extent flux transfer from the dayside to the nightside.