Temporal characteristics of irregular magnetic pulsations and intervals of pulsations of diminishing periods (IPDP) plasma wave events observed in association with low-latitude auroras are reported. The two most significant issues are the particle spectrum associated with low-latitude auroras and convective growth rate modeling for the IPDP plasma wave events. In particular, it is shown that the growth rate is sensitive to variations in oxygen-ion kinetic energy in addition to movements of the source region. The frequency increase in the dynamic spectrum of a low-latitude IPDP plasma wave event can be explained in terms of the variation of the kinetic energy of the precipitating oxygen-ion stream during low-latitude auroras. ¿ 1998 American Geophysical Union