Drift-Shell Splitting by Internal Geomagnetic Multipoles.
Rept. for Jan-May 72,
AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS
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Computations on an 80-coefficient model of the earths field illustrate the topography of the magnetic equatorial surface on which B dot del B O and the geometry of the drift shells of geomagnetically trapped particles. Individual terms in the spherical-harmonic expansion offset-dipole coordinates of the geomagnetic scalar potential Vr, theta, phi are either even or odd in cos theta, where theta pi2 denotes the dipole equator. Terms that unlike the dipole are even in cos theta tend to warp the equatorial surface, but do not in first order distort particle drift shells radially nor split the drift shells of particles having different equatorial pitch angles. Azimuthally asymmetric terms that are odd in cos theta do cause shell splitting in first order. Shell splitting at large L values neglecting deformation of the earths field by the solar wind is found to be dominated by the geomagnetic octupole. At L about 1, shell splitting is strongly enhanced by the South American and South African anomalies. When combined with pitch-angle diffusion caused by atmospheric scattering, these results may be able to account for anomalous radial diffusion of inner-zone electrons. Author
- Atmospheric Physics