Effects of tailward stretching geomagnetic field on drift motion of plasma particles in the magnetospheric equatorial plane

Abstract Drift paths of electrons and protons are calculated in the equatorial plane of the superquiet (SQ) and superdisturbed(SD) Mead-Fairfield magnetospheric models in order to study effects of tailward stretching geomagnetic field on drift motion of plasma particles. Magnetospheric electric fields in the equatorial plane are given by vector sums of uniform dawn-dusk electric field of 0.1 mV/m or 0.4 mV/m and corotation electric field projected onto the equatorial plane from the earth's surface along the MF geomagnetic field lines. All particles start from a geocentric circle of 17 earth radii (R E ) in the tail equatorial plane. The late-evening stagnation point for zero-energy particles and low-energy electrons is produced by the anticlockwise corotation drift larger than the sunward electric-field drift in the outer magnetosphere. The late-morning stagnation point for energetic protons and the late-afternoon stagnation point for energetic electrons result from small radial gradient of the MF geomagnetic field in the late-morning and the late-afternoon outer magnetosphere respectively.