CONNECTIONS BETWEEN HIGH-LATITUDE AND MIDDLE-LATITUDE PULSATIONS

Pulsation data from the mid-latitude observatory Nagycenk have been compared with those of the auroral zone station Troms-phi and of the high-latitude stations Hornsund and Ny Alesund. The comparison has shown a rather high correlation between the Pc3 pulsation activities at all sites, with an independent component at the highest latitudes. Mid-latitude Pc3 is also correlated with high-latitude Pc4 and Pc5. The results can be explained by two main types of (mid-latitude) pulsations occurring simultaneously or independently at different times. The first has constant periods up to the highest latitude studied and is thought to be of extramagnetospheric origin. Magnetospheric signals, however, have-at least in certain events-periods increasing with increasing latitude, up to the high-latitude stations.