Variability of theS q focus position in the South American continent

The daily variation of the H component at Pilar (31.7°S, 63–9°W) and Trelew (43.3°S, 65.3°W) in the South American continent indicates a great variability in amplitude from season to season and even from day to day. However, Pilar always remains equatorward of the southern S_q, focus. On the other hand, Trelew is in most cases slightly poleward of the S_q, focus; but the focus has large latitudinal excursions above and near Trelew. A cause of this variability could be the encroachment of polar ionospheric current systems into the low latitude ionospheric S_q, current system.