Studies of the magnetospheric substorm: 2. Correlated magnetic micropulsations and electron precipitation occurring during auroral substorms

The temporal characteristics of geomagnetic micropulsations and the associated energetic auroral-zone electron precipitation are presented as a function of local time. In the midnight region, broadband noise bursts and impulsive electron precipitation are related to the auroral breakup. Band-limited irregular (Pi 1) micropulsations and modulated electron precipitation of 5- to 10-sec period occur from 0200 to 1000 in conjunction with negative bays. In the local-time interval 1000–1500, quasi-sinusoidal (Pc 3) micropulsations are related to modulated electron precipitation of 20- to 40-sec period. Power spectrum and digital sonagram analysis for the band-limited irregular and quasi-sinusoidal micropulsations and the modulated electron precipitation are presented. Around local noon, magnetic impulses are correlated with electron microbursts. From 1500 to 2200, sweepers or IDPD events and premidnight micropulsations show no relationship to electron precipitation, but they are closely related to auroral substorms. Pearl pulsations appear to have no definite association with either electron precipitation or substorms.

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