X. Zhang et al., PROPAGATION CHARACTERISTICS OF PC-3 COMPRESSIONAL WAVES GENERATED AT THE DAYSIDE MAGNETOPAUSE, J GEO R-S P, 98(A9), 1993, pp. 15403-15410
New, three-dimensional ray tracing of Pc 3 compressional waves from th
e magnetosheath reveals that the magnetosphere can present a major pro
pagation barrier to the penetration of these waves to the plasmasphere
. This barrier is the ion-ion cutoff between the He+ and O+ gyroresona
nces. As a result of the frequency-dependent location of this cutoff,
the magnetosphere behaves like a filter for Pc 3 compressional waves,
and only low-frequency components of Pc 3 compressional waves can pene
trate to inner magnetosphere. Results are in agreement with previous s
atellite observations. This ''filter action'' strongly depends on the
relative concentration of He+ and O+ and is therefore sensitive to sol
ar and magnetic activity. Ray-tracing results are based on a cold plas
ma dispersion relation, a semi-empirical model of plasma density, and
the Mead-Fairfield magnetic field model.