Evidence for reverse draping of magnetosheath field around the magnetosphere in IMP 8 observations for northward interplanetary magnetic field

Abstract

Fedder and Lyon [1995] recently showed the results from a global three‐dimensional magnetohydrodynamic (MHD) model of the solar wind interaction with the Earth's magnetic field for northward interplanetary magnetic field (IMF) that exhibited a “tadpole”‐shaped closed magnetosphere. One consequence of this configuration is that the inner magnetosheath or boundary layer fields exhibit reverse draping at the flanks compared to what is expected from the classical gas dynamic picture. This reverse draping, which occurs as a result of nearcusp merging in the MHD model, appears to be present in the statistical field pattern observed on IMP 8 at x ≈ −25–31 RE. The implication is that boundary layer field configurations for northward IMF produce very different J × B forces on the local boundary layer plasma than would be inferred from classical draping and thus may be responsible for some of the observed IMF dependence of the low‐latitude boundary layer properties.