EISCAT observation on plasma drifts connected with the Aureld-VIP rocket and the Viking satellite

Coordinated simultaneous measurements with the EISCAT incoherent scatter radar, Aureld-VIP sounding rocket, and Viking satellite are described. Background measurements from EISCAT provide us with the development of global plasma convection during the rocket night. The observed convection pattern is very distorted, with the eveningside reversal occurring at unusually low latitudes. On the morningside it withdraws back poleward from the measurement area. Viking particle measurements over the oval indicate a very complicated auroral topology with two sectors of boundary plasma sheet (BPS) and central plasma sheet (CPS) particles. The situation is interpreted as an intrusion of the evening side BPS into the morningside, which is also consistent with the convection pattern measured by EISCAT. Local measurements with the sounding rocket and radar indicate that the rocket flew in the northern part of the evening BPS area, approaching the inner transition region from BPS to CPS in its northward motion, thus confirming the existence of such a boundary