FIELD-ALIGNED CURRENTS IN THE HIGH-LATITUDE, HIGH-ALTITUDE MAGNETOSPHERE - POLAR INITIAL RESULTS

Magnetic field measurements obtained by the POLAR spacecraft are used to map out the region 1 and region 2 field-aligned current systems in the dayside hemisphere at radial distances of close to 8 Earth radii a bove the northern polar cap. The extrapolated invariant latitude of th ese currents is quite variable. The equatorward edge of the region 1 s ystem ranges from 73 to 83 degrees degrees invariant latitude. The sen se of both systems reverses across noon as expected. The strength of t he currents also varies, averaging about 0.03 A/m for the region 1 cur rents and 0.01 A/m for the region 2 currents. Over the dayside hemisph ere this amounts to about 1.5 million amps flowing down and up the fie ld lines in the region 1 system and about 0.5 million amps in the regi on 2 system. These numbers and the behavior of the current are quite c onsistent with low-altitude observations.