THE SUBSOLAR MAGNETOSHEATH AND MAGNETOPAUSE FOR HIGH SOLAR-WIND RAM PRESSURE - WIND OBSERVATIONS

On a rapid inward pass through the subsolar magnetosheath (MSH) and ma gnetopause (MP), the WIND spacecraft initially encountered a moderatel y-compressed low-magnetic shear MP (at a radial distance of 8.6 R(E)), followed by multiple crossings of a high-shear MP (at 8.2 R(E)). The large shear resulted from a southward turning of the external MSH fiel d. Strong magnetic field pile-up, a plasma depletion layer (PDL), and plasma flow acceleration and rotation to become more perpendicular to the local magnetic field were observed in the MSH on approach to the l ow-shear MP. At the high-shear MP, magnetic reconnection flows were de tected, and there are some indications that plasma depletion effects w ere weak or absent in the adjacent MSH. We attribute the changes in th e MP and MSH properties to the sudden rotation of the MSH field direct ion. In essence, the structure of the MP regions under the unusually h igh solar wind ram pressure condition in this case does not seem to be qualitatively different from that observed under more typical (less c ompressed) conditions. Also similar to previous observations, the mirr or mode is marginally unstable in the MSH proper, but is stable in the PDL. In this region, the proton temperature anisotropy is inversely c orrelated with beta(p parallel to). Finally, the electron distribution s are observed to be anisotropic (T-e perpendicular to/T-e parallel to similar to 1.3) throughout the entire MSH.