Pi 1–2 magnetic field pulsations on dayside cleft field lines

摘要: TYPE Pi 1–2 magnetic field pulsations, T = 1–150 s, have a broad-band, noise-like character and tendency to occur during active aurorae magnetospheric substorms1,2. It is well-known that type pulsations observed in the night–morning sector substorms maximise amplitudes along auroral oval1,2. But relation of activity day oval has not been clear. This particular interest because seems coincide approximately with feet dayside cleft lines; precise between oval, however, yet established (S. I. Akasofu, personal communication). Dayside lines usually terminate geomagnetic latitudes 75° 80°. We show here intense appeared at College on two occasions when came down latitude, 64.7° N, times was midday sector. Further, it shown an flux particle precipitation into ionosphere occurred second occasion, 4 August 1972.