Observation and modeling of compressional Pi 3 magnetic pulsations

摘要: Compressional magnetic pulsations with irregular waveforms and periods longer than 150 s (here termed Pi 3) have been studied by using data from Active Magnetospheric Particle Tracer Explorers Charge Composition Explorer (AMPTE/CCE) GOES 5 6 in the dayside magnetosphere compared signatures on ground at low latitudes Kakioka station (L = 1.25). On ground, appear horizontal component. A study of 17 such concurrent events during a 2-month period 1986 reveals following pulsation characteristics. (1) The peak-to-peak amplitudes space (δBT) (δH) are comparable range 0.5–7 nT. (2) can be seen all local times, even midnight, while geostationary orbit they observed only clear amplitude maximum noon. (3) lag those CCE near noon, increases as time separation between increases. is 1–2 min when nightside it dayside. (4) noon varies systematically about 2 per hours separation. These observations indicate that some 3 band origins. position dependence explained well changes magnetopause current, which turn presumably caused solar wind dynamic pressure. lags consistent signal propagation MHD fast mode, but variation space-ground must attributed to another mechanism.