IONOSPHERIC PARAMETERS DERIVED FROM ECHO II RADAR RETURNS DURING SOLAR MINIMUM CONDITIONS.
NAVAL RESEARCH LAB WASHINGTON D C
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Radar returns from the Echo II satellite 1964-4A were analyzed for Faraday rotation effects in order to ascertain their utility in deducing both the subsatellite electron content and the equivalent slab thickness of the daytime ionosphere. The following conclusions were reached a The subsatellite electron content generally exhibits a large variance, but its average value tends to be largest near midday and decreases with increasing solar zenith angle. b The daily equivalent slab thickness exhibits no marked variation between 0800 and 1800 EST, although midafternoon values are somewhat in excess of prenoon values. c The seasonal equivalent slab thickness has its minimum in local winter and its maximum in local summer the equinox values are intermediate, with the autumnal equinox exhibiting higher computed values than the vernal equinox period. d The mean scale height Hs and the mean neutral gas temperature T for the ionosphere were found to be 94 km and 1582 K, respectively, during daytime hours. The daytime ionosphere was found to be 500 K warmer in summer than in winter, with the mean equinox temperature being close to the all-season average. e No pronounced correlation with Zurich sunspot number of decimetric solar flux was discernible, which was probably due to the fact that statistical variations in the observations exceeded the real variations which might have occurred as a result of solar activity changes. f No correlation with the magnetic index K was noted. These conclusions are based on radar echo data obtained during the recent period of minimum solar activity. Author
- Atmospheric Physics
- Radiofrequency Wave Propagation
- Unmanned Spacecraft