Survey on the Magnetic Structure of the Neutral Sheets in Earth's Magnetotail

Abstract

Based on the multipoint magnetic observations of Cluster from 2001 to 2004, the magnetic field structure in magnetotail Neutral Sheet （NS） is statistically surveyed. The results are as follows. In NS, <i>a</i> cubic function is selected to reveal the relation between <i>y</i> （GSM） and positional parameter <i>z</i>. The relation between <i>y</i> and magnetic field values indicates that the magnetic field is weak at midnight region and strengthens gradually at the duskside and dawnside. The relation between <i>y</i> and curvature radius is expressed by <i>a</i> quadratic function. And <i>R</i>_c of flattened CS is less than that of the normal CS. <i>B</i>_<i>y</i> determines the orientation of MFLs' configuration. The polar angle of the curvature vector is affected by the NS configuration. In addition, the correlation between the polar angle of the curvature vector and <i>z</i> is higher. The polar angle of the normal of the osculating plane is uncertain in the center area. The relation between the azimuthal angles of the curvature vector （the normal of the osculating plane） and <i>y</i> is negatively correlated. An empirical model applied to <i>yz</i> plane of the three-dimensional structure of the magnetic field lines in the NS are developed, and it is represented as <i>a</i> function of the positional parameter <i>y</i>. Finally, the current density is also statistically surveyed.