X-ray observations in the SAA—Pulsations in electron precipitation accompanied by Pc4 events

A balloon experiment conducted on December 20, 1994, in the South Atlantic Anomaly (SAA) region, detected events with increases in x-ray flux due to electron precipitation coincident with a mild substorm activity. For the first time in the SAA, the analysis of the x-ray flux associated with the electron precipitation and the geomagnetic H-field component showed simultaneous Pc4 pulsations at periods in the range 95 to 100s. Analysis of a prominent precipitation event of this flight showed direct correlation between the pulsation strength in the x-ray and in the magnetic data and are related to the intensity of the precipitation. While the substorm associated electric fields and currents in the ionosphere can induce amplification of Pc4 pulsations, the x-ray pulsations due to electron precipitation may be related to wave modulated pitch angle scatterings.