Solar wind interaction with the Earth's magnetic field: 1. Magnetosheath

Properties of plasma and magnetic field within the magnetosheath in the period December 1968 to December 1969 are presented as observed by the European satellite Heos 1. Three states of the magnetosheath plasma have been distinguished on the basis of different upstream conditions and are characterized by low magnetosonic Mach number (M1 < 3) and low β, high values of M1 and β and absence of upstream waves, and presence of upstream waves. The distribution function of proton velocities and the magnetic turbulence in the magnetosheath have been studied in connection with these three upstream situations.