Abstract
Whistler dispersion, measured on the ISIS 2 satellite, at an altitude of
1400 km, showed a variation with latitude from about
4.5s1/(2) at a magnetic latitude (λ) of 30° to
about 1 12+/-2s1/(2) at the equator. Frequently, fractional
hop whistlers were observed from both hemispheres with dispersions which
converged to the same value at the equator. Ray tracing calculations
revealed that whistler mode signals of different frequencies take
different paths from a source on the ground to the satellite and yet
their dispersion is indistinguishable from the Eckersley form. The
extent of the entry region to the ionosphere depends on the satellite
location and may be more than 300km for different frequencies. The
fractional hop whistlers frequently excite proton whistlers and their
crossover frequencies have been used to determine fractional hydrogen
ion concentrations. The measurements show that the average fractional
H+ concentrations at 1400km increase from about 0.80 at
λ = 25° to 0.88 at the equator.
Original language | English |
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Pages (from-to) | 1217-1222 |
Journal | Journal of Atmospheric and Terrestrial Physics |
Volume | 59 |
Publication status | Published - 1 Jul 1997 |