POLARIZATION OF Pc 1 AND IPDP PULSATIONS CORRELATED WITH PARTICLE PRECIPITATION.

The correlation of Pc 1 and IPDP pulsations with particle precipitation shows that the waves are left (L) polarized when observed simultaneously with precipitation. This is consistent with theoretical understanding of the generation of the pulsations as an L wave in the magnetosphere and the L wave propagation through the ionosphere with horizontal ducting of the R wave. It is suggested that L polarization of Pc 1 and IPDP locates the ULF source field line. Three events studied were IPDP correlated with riometer absorption. The observations strongly support the inward convecting source model for the generation of IPDP. On the other hand, the origin of the particles (presumably electrons) responsible for the riometer absorption is still an open question.