Polarization of Pc 1 pulsations at high and middle latitudes

Polarization studies of hydromagnetic emission events have been undertaken over a 10-month period in 1971–1972 at Great Whale River, Quebec, Canada; Boulder, Colorado; and College, Alaska. The occurrence of events common to all three stations suggests that transverse ionospheric duct propagation of Pc 1 signals is possible at both high and middle latitudes. Polarization ellipse major axis azimuths, ellipticities, and perturbation vector rotation directions in the plane of the earth's surface often show consistent and related behavior at high and middle latitudes when statistical samples and individual events are considered. Erratic polarization associated with geomagnetic storm activity is observed at high latitudes but not at low latitudes. The results are interpreted in terms of the source location at ionospheric heights, ionospheric duct propagation, and ground induction effects.