Simultaneous measurements of the auroral zone particle precipitation and the ion convection velocity by Atmosphere Explorer show a consistent difference between the location of the poleward boundary of the auroral particle precipitation and the ion convection reversal. The difference, of about 1.5 ¿ of invariant latitude, is such that some part of the antisunward convection lies wholly within the auroral particle precipitation region. The nature of the convection reversals within the precitation region is consistent with a region in which the convection electric field is generated on closed field lines that connect in the magnetosphere to the low-latitude boundary layer.