Simultaneous Relativistic Electron and Auroral Particle Access to the Polar Caps during Interplanetary Magnetic Field Bz Northward: A Scenario for an Open Field Line Source of Auroral Particles.

摘要

The large magnetic storm of February 1986 provides a unique opportunity to assess whether existing open-closed theories of the magnetosphere can consistently account for precipitating particle signatures measured at 840 km under a wide variety of solar wind and solar particle conditions. The simultaneous observation are prepared for relativistic electrons associated with a solar proton event and of auroral ions and electrons associated with a polar cap are event, made across the central polar cap using detectors on board the Defense Meteorological Satellite Program (DMSP) satellites. On February 7 while a solar proton event was still in progress, polar cap arc activity (interplanetary magnetic field (IMF)B2 large and positive, Kp = 3+) occurred prior to a prolonged period of oval arc activity (IMF B2 large and negative, Kp = 6-). Throughout these periods the following are identified: the equatorward edge of the relativistic electron precipitation; the outer zone electron poleward and equatorward boundaries; the equatorward auroral electron and ion boundaries; and the auroral electron transition boundary. The history of the boundaries is presented as the transition from intense polar cap activity to intense auroral oval activity takes place. The data clearly show that the polar cap region of relativistic electron precipitation does not change significantly as the sign of B2 changes. On the other hand, the boundary layer population, which contains auroral arcs and 1- to 10-keV ion precipitation, expands to fill most of the polar cap for B2 northward and greatly contracts as B2 turns southward. The expansion is not symmetric between poles. Reprints. (jhd)