RELATIONSHIP BETWEEN BIRKELAND CURRENT REGIONS, PARTICLE-PRECIPITATION, AND ELECTRIC-FIELDS

Data from eight DMSP F7 satellite passes coincident with Sondrestrom r adar observations have been examined to determine how the large-scale dayside Birkeland currents are related to the particle precipitation r egions and to the convection pattern. The classification schemes recen tly developed from DMSP particle data were adopted. The observations w ere limited to the prenoon local time hours and led to the following c onclusions: (1) The local time of the mantle currents (which were trad itionally called cusp currents) is not limited to the longitude of the cusp proper, but covers a larger local time extent. (2) The mantle cu rrents flow entirely on open field lines (where ''open field lines'' i s defined as a region where the ion precipitation and electron precipi tation have the characteristics of plasma mantle, cusp, or polar rain. ) This confirms and extends to all local times similar results obtaine d from other observations. (3) About half of region 1 currents flow on open field lines. This is consistent with the assumption that the reg ion 1 currents are generated by the solar wind dynamo and flow within the surface that separates open and closed field lines. (4) More than 80% of the Birkeland current boundaries do not correspond to particle precipitation boundaries. Region 2 currents extend beyond the plasma s heet poleward boundary; region 1 currents flow in part on open field l ines; mantle currents and mantle particles are not coincident. (5) On most passes when a triple current sheet is observed (region 2, region 1, and mantle currents), the convection reversal is located on closed field lines. When only two current sheets are observed (either region 2/region 1, or region 1/mantle currents), the convection reversal is o n open field lines. (6) The data appear to be more consistent with a t opology such that mantle currents are an extension of region 1 current s, rather than a separate system located poleward of the region 1 curr ent system.