Recent studies have shown that instead of homogeneous steady convection the Earthward plasma flow in the midtail usually appears to have short impulsive bursts with very variable characteristics. Here we concentrate on satellite observations of plasma bubble events in which the high-speed flows are accompanied by decreases in plasma pressure. We have selected several isolated bubble events observed by the AMPTE/IRM-satellite while its footpoint was close to the EISCAT Magnetometer Cross. Bubble signatures were recorded as close to the Earth as X_gsm ∼ -11R_E. In all events the ground magnetic field showed distict small variations (ΔB around 50 nT) with longitudinal scale sizes ≤ 0.5 LT-hrs. In most cases the magnetic field observations are consistent with Hall-current vortices forming in ionosphere at the footpoint of localized field-aligned currents. These observations support the view that the polarization electric field inside a bubble discharges via field-aligned currents to the ionosphere.