MAGNETOSHEATH DENSITY-FLUCTUATIONS AND MAGNETOPAUSE MOTION

The interplanetary magnetic field (IMF) orientation controls foreshock densities and modulates the fraction of the solar wind dynamic pressu re applied to the magnetosphere. Such pressure variations produce bow shock and magnetopause motion and cause the radial. profiles for vario us magnetosheath parameters to sweep inward and outward past nearly st ationary satellites. We report ISEE 2 observations of correlated densi ty and speed fluctuations, and anticorrelated density and temperature fluctuations, on an outbound pass through the northern dawnside magnet osheath. Densities decreased when the magnetic field rotated southward and draped about the magnetopause. In the absence of any significant solar wind density or dynamic pressure variations, we interpret the ma gnetosheath fluctuations as evidence for radial magnetosheath motion i nduced by variations in the IMF orientation.