The horizontal propagation of Pc1 pulsations in the ionosphere
Abstract
The propagation properties of the various elements of the planewave angular spectrum of a Pc1 pulsation signal in the ionosphere are determined by a fullwave numerical analysis. A spectral component is characterized by the wavevector azimuthal direction, and the Snell constant S. The isotropic Rmode transmission coefficient to ground is fairly flat for S ⩽ 400, but thereafter ( S > 500) drops rapidly with increasing S. Coupling of energy from the fieldguided Lmode to the Rmode occurs along the entire length of the Lmode trajectory within the ionospheric duct in which the Rmode can propagate. Within the duct, the Rmode attenuation is determined largely by R to Lmode coupling, which is larger for EW than for NS azimuths, especially for steep angles of incidence ( S < 100). This should lead to enhanced injection of energy into EW high altitude, high velocity paths, but to higher EW attenuation at oblique angles. For oblique propagation ( S ⩾ 200) horizontal group velocities are slightly higher than the Alfvén phase velocity at the Flayer peak, but about twice as high for steep angles ( S ≈ 100).
 Publication:

Planetary and Space Science
 Pub Date:
 January 1980
 DOI:
 10.1016/00320633(80)90104X
 Bibcode:
 1980P&SS...28...61A
 Keywords:

 Geomagnetic Micropulsations;
 Ionospheric Propagation;
 Plane Waves;
 Coupled Modes;
 Magnetohydrodynamic Waves;
 Numerical Analysis;
 Snells Law;
 Wave Interaction;
 Geophysics