磁尾中性片与磁尾正交曲线坐标系

根据磁尾中性计随地磁倾角变化的特点用光滑函数拟合中性片曲面模式，并用ＩＳＥＥ卫星的磁场资料来确定曲面参数．本中性片模式既保持了中性片的基本变化特征，又可以在近地处光滑过渡到赤道面．在此基础上，建立了一个以中性片曲面为坐标面的磁尾正交曲线坐标系．这个坐标系随地磁倾角的变化而变化，用这个坐标系可将不同的地磁倾角的磁场位形变换成地磁倾角为零时的标准形式，从而便于分析卫星的观测数据．

A CONTINUOUS NEUTRAL SHEET MODEL AND A NORMAL CURVE COORDINATE SYSTEM IN THE MAGNETOTAIL

A model of the continuous equatorial-neutral sheet is developed. This model is expressed with a smooth function, whose parameters are determined by the magnetic data of the ISEE-2 satellite, and it can very smoothly connect the geomagnetic equatorial plane with the magnetotail neutral sheet changing about with the earth's tilt angle. Based on this analytic model, a normal curve coordinate system is set up, in which the neutral sheet become one of the coordinate surface. The new coordinate system will change with the earth's tilt angle and thus can almost offset the tilted effect on the pattern of geomagnetic field in the magnetotail region.