Solar wind plasma speed, the interplanetary magnetic field, the geomagnetic field, and the galactic cosmic ray intensity near the Earth all vary periodically in response to solar rotation. This study addresses specifically the problem of defining observationally the strength and period of recurrence in lists of impulsive events. The analysis strategy is to determine the frequency with which events are separated by a given time interval. Comparison of this frequency with that expected for events which occur randomly establishes the significance of the periodicities observed. Specifically, the analysis of interevent intervals in K-coronal data will compare the differential rotation of bright and dark coronal regions. With these coronal results, analysis of intervals between fast solar wind streams locates a mean latitude of origin for the solar stimulus for interplanetary recurrence. Impulsive geomagnetic disturbances as a proxy for interplanetary shocks, and their recurrence properties will be compared with similar analyses of recurrent cosmic ray variations. Longer term recurrence of geomagnetic disturbance will decide if there are terrestrial effects of the recently reported 150 day periodicity in solar flares.
