Auroral-zone electron precipitation events observed before and at the onset of negative magnetic bays

摘要: Abstract Balloon recordings of bremsstrahlung X-raya from precipitating electrons are presented, showing impulsive X-ray events just at the onset bay activity as well weaker and smoother electron precipitation before bay, latter apparently being connected with a growth phase same substorm. The pre-bay generally very smoothly varying events, but show modulation effects associated occurrence irregular magnetic pulsations. start abruptly together Pi 2 pulsations onset, also effects, so that maxima in flux tend to accompany H -component auroral-zone stations. These have shorter period than simultaneous mid-latitude 2, which we take indicate occur on field lines close inner edge neutral sheet.