A statistical study of Pc3-Pc5 magnetic pulsations observed by the AMPTE/Ion Release Module satellite

Magnetic field data from the Active Magnetospheric Particle Tracer Explorer s/Ion Release Module satellite are used to complete a statistical study yie lding occurrence rates of a number of different types of pulsations. Two ho ur panels of dynamic spectra and detrended line plots were inspected to det ermine occurrence rates over all local times from L = 6 to L = 20. Event ty pes include fundamental field line resonances, harmonic resonances, storm t ime pulsations, and signatures of bursty bulk flows and fast flows. However , we also include observations of Pc3 compressional pulsations and note the ir association with harmonic events. Likewise, we include high-frequency ev ents (40-70 mHz) and show a relation to storm time pulsations. On the basis of the occurrence distributions, we are able to make a number of conclusio ns. We determine that the excitation source of fundamental resonances is li kely band limited from 3 to 10 mHz and that harmonic resonances are at leas t sometimes associated with compressional Pc3 pulsations. Storm time pulsat ions, compressional in nature, are sometimes associated with relatively hig h frequency transverse events and often occur in regions very close to the magnetopause. On the basis of other works that associate these pulsations w ith instabilities in the partial ring current, we suggest that particles th at form the partial ring current may extend to the magnetopause during stor ms and substorms. Finally, we note that bursty bulk flows and fast flows in general have a magnetic signature that is predominantly compressional, and we discuss the relevance this may have regarding substorm dipolarization.