Observations of scintillations for 5 years at about 53°N∧ have been used to attempt to identify the sources of the kilometer-scale irregularities in this region. The scintillation observations show that there are long-time, and possibly seasonal variations, which are associated with magnetic activity. The diurnal variation of scintillations shows a nighttime maximum. This occurs before midnight in summer and about 3 hours postmidnight the rest of the year. The correlation of scintillations and magnetic activity is positive in winter, negative in summer, and uncorrelated in equinox. In order to explain these observations, at least three sources of irregularities are required: (1) A local source which is active at sunset in summer. (2) A source at higher latitudes; the irregularities are convected south during nighttime to 53°N∧. This source is most prevalent in winter. (3) A local source which is active over intervals of a few days and may be associated with plasmapause phenomena such as stable auroral red arcs.