Sources of the cusp plasma for the different sign of IMF By

The importance of the interplanetary magnetic field (IMF) direction for the cusp formation was dicovered a long time ago. A sign of the IMF Bz component is believed to be responsible for a location of the plasma entry into the cusp. The paper uses the INTERBALL-1 and MAGION-4 data to study the high-altitude cusp topology for different IMF By orientations. The study reveals the importance of IMF horizontal components on the cusp configuration as well as on small-scale processes at the outer cusp. We discuss an influence of the tilt angle of the Earth's dipole on these processes