Possible evidence of flux transfer events in the polar ionosphere

Abstract

We present magnetic field data from the cusp‐latitude South Pole station that exhibit, under appropriate local time and interplanetary magnetic field conditions, the signature expected in the ionosphere from a flux transfer event (FTE) at the magnetopause. In particular, the model of multiple X‐line reconnection at the magnetopause predicts field‐aligned currents in helical flux tubes, with transverse magnetic fields propagating as Alfvén waves toward the ionosphere. The distinctive magnetic signature at a polar cap magnetic station, particularly in the vertical component, can be used to infer the signs of the By and Bz components of the interplanetary magnetic field. Copyright 1986 by the American Geophysical Union.