Cluster vision of the magnetotail current sheet on a macroscale

Abstract

With Cluster 2001-2003 observations at ∼20 R_E downtail we determine the cross-tail current sheet configuration via mapping of the neutral sheet positions and direct measurements of the sheet inclination. The warping effect tilts both flanks of the sheet up to 40° in the YZ GSM plane, while the gradual hinging effect tilts the sheet up to 10-20° roughly in the XZ plane. These findings are in agreement with the recent neutral sheet model of Tsyganenko and Fairfield (2004). Nonuniform response of the neutral sheet B_y to IMF was also revealed. Typical IMF B_y penetration efficiency was 40-60%. However, efficiency for positive IMF B_y was below 20% at both flanks. Therefore at the flanks of the neutral sheet the normal magnetic field component (along the normal to the warped sheet) is generally larger than the shear component (along the current).