Latitudinal distribution of auroral arcs velocity

Velocity latitudinal distribution of vd auroral arc meridional drift in the auroral zone midnight sector is investigated. vd value is shown to increase from 100m/s near auroral oval southern boundary up to 400m/s close its near-polar boundary. Arc movements, observed in the ionosphere, are projected along geomagnetic field force lines into plasma layer, distribution of Ey electric field y-component in the magnetotail is investigated on this basis. It is shown, that at distances x=(15-60) RE (RE - is the Earth radius) from the Earth the electric field in the first approximation is homogeneous one; at x<13RE Ey field reduces in proportion to the Earth approaching