The Semiannual Variation in the Upper Atmosphere (900-1200km) at Solar Minimum.

摘要

A new method has been developed that uses satellite along-track position errors to obtain information on atmospheric densities at altitudes of 900 to 1200 km. The data based used was the daily tracking results from the Navy Navigation Satellite System (NNSS). Densities derived from these data (for the years 1974-76) show a pronounced semiannual variation, with the April/October maxima exceeding the August/January minima by factors of 2 to 4. The variation is more pronounced than was previously reported, and double the best current modeled variation. The current resolution with this technique is estimated to be 1 x 10 to the -19th power gm/cu cm, or about 10% of the total density at these altitudes. (Author)