Observations of solar wind penetration into the earth's magnetosphere - the plasma mantle

The large database provided by the continuous coverage of the Defense Meteorogical Satellite Program polar orbiting satellites constitutes an important source of information on particle precipitation in the ionosphere. This information can be used to monitor and map the earth's magnetosphere (the cavity around the earth that forms as the stream of particles and magnetic field ejected from the sun, known as the solar wind, encounters the earth's magnetic field) and for a large variety of statistical studies of its morphology and dynamics. The boundary between the magnetosphere and the solar wind is presumably open in some places and at some times, thus allowing the direct entry of solar-wind plasma into the magnetosphere through a boundary layer known as the plasma mantle. The preliminary results of a statistical study of the plasma-mantle precipitation in the inosphere are presented. The first quantitative mapping of the ionospheric region where the plasma-mantle particles precipitate is obtained. 12 refs