RELATIONSHIP BETWEEN THE IMF MAGNITUDE AND PC 3 MAGNETIC PULSATIONS IN THE MAGNETOSPHERE

Relationships between the interplanetary magnetic field (IMF) magnitude and pulsation frequencies in the Pc 3-4 range simultaneously observed both at the synchronous orbit and at low latitudes on the ground are described. A theoretical discussion is then presented on how these observations can be interpreted in terms of the characteristic frequency of compressional Pc 3-4 magnetic pulsations in the magnetosphere on the basis of the well-established ion cyclotron resonance mechanism between magnetosonic mode of low-frequency upstream waves and narrowly reflected ion beams in the earth's foreshock. 68 refs.