EVIDENCE FOR REVERSE DRAPING OF MAGNETOSHEATH FIELD AROUND THE MAGNETOSPHERE IN IMP-8 OBSERVATIONS FOR NORTHWARD INTERPLANETARY MAGNETIC-FIELD

Fedder and Lyon [1995] recently showed the results from a global three -dimensional magnetohydrodynamic (MHD) model of the solar wind interac tion with the Earth's magnetic field for northward interplanetary magn etic field (IMF) that exhibited a ''tadpole''-shaped closed magnetosph ere, One consequence of this configuration is that the inner magnetosh eath or boundary layer fields exhibit reverse draping at the flanks co mpared to what is expected from the classical gas dynamic picture, Thi s reverse draping, which occurs as a result of near-cusp merging in th e MHD model, appears to be present in the statistical field pattern ob served on IMP 8 at x approximate to -25-31 R(E). The implication is th at boundary layer field configurations for northward IMF produce very different JxB forces on the local boundary layer plasma than would be inferred from classical draping and thus may be responsible for some o f the observed IMF dependence of the low-latitude boundary layer prope rties.