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Indirect phase height measurements of the lower ionosphere compared with rocket measurements of D-region electron density

: Cossart, G. von; Sprenger, K.; Pakhomov, S.V.

Journal of Atmospheric and Terrestrial Physics 48 (1986), Nr.4, S.355-63
ISSN: 0021-9169
Fraunhofer HHI ()
d-region; electron density; ionospheric electromagnetic wave propagation; radiowave propagation; lower ionosphere; d-region electron density; rocket-measured electron density profiles; ground-based indirect phase height measurements; lf; volgograd; magnetoionic ray theory; ionization; reflection level; real geometric height; seasonal variations; diurnal variation

A comparison between rocket-measured electron density profiles of the lower ionosphere and the results of ground-based indirect phase height measurements in the LF range, carried out near the Soviet rocket sounding station Volgograd over several years, confirms-to a first-order approximation-the height of the level of electron density which according to magnetoionic ray theory is necessary for reflection of the waves. In a second-order approximation, however, an additional phase path change has to be taken into account, which is caused by the ionization below the reflection level. This makes the observed phase height always slightly smaller than the real geometric height, on average by -1 km, but in extreme cases by up to -4 km, depending on the actual height of electron density below the reflection level. Due to systematic diurnal and seasonal variations of this gradient, the amplitude of the diurnal variation of the observed phase height is found to be slightly larger than that of the real geometric height, whereas the reverse is true for the seasonal variation at constant solar zenith angle.