VLF goniometer observations at halley bay, Antarctica—II. Magnetospheric structure deduced from whistler observations

Thunderstorms, Lightning, Sprites and Magnetospheric Whistler-Mode Radio Waves

“…Later on, the horizontal components of the wave fields were measured along with the vertical components. These measurements were used to determine the polarization and arrival direction of the waves (Sagredo and Bullough, 1973;Hayakawa et al, 1986) and used to pin-point where the downcoming whistler entered the Earthionosphere waveguide (Hayakawa, 1993).…”

Density duct formation in the wake of a travelling ionospheric disturbance: Murchison Widefield Array observations

“…Radio propagation is powerful probe of the density distribution of magnetospheric and ionospheric plasma. The refractive, diffractive and dispersive effects that free electrons have on radio signals enable structure to be deduced from whistler spectrograms [Sagredo and Bullough, 1973;Singh et al, 1994], observations of cosmic radio sources [Wild and Roberts, 1956;Coker et al, 2009;Helmboldt and Intema, 2014;Loi et al, 2015a], sounding and radar scattering experiments [Hunsucker , 1991], and satellite dual-frequency delay measurements [Mannucci et al, 1998;Bernhardt and Siefring, 2006;Hawarey, 2006]. The geomagnetic field imposes significant anisotropy in the shapes of density irregularities, since electron and ion mobilities are much larger parallel than perpendicular to the magnetic field [Calvert and Warnock , 1969;Booker , 1979].…”

“…Properties deduced from observations and modelling [Park , 1970;Sagredo and Bullough, 1973;Walker , 1978;Lester and Smith, 1980] are cross-sectional widths of 10-100 km, enhancements and depletions of 1-10% relative to the ambient density, and timescales of growth and decay of hours to days. Whistler-mode waves, which can be trapped and guided by these ducts, are believed to play a major role in the precipitation of energetic particles through resonant interactions [Voss et al, 1984;Burgess and Inan, 1993;Abel and Thorne, 1998].…”