Abstracts Physics

Studies of irregularities in electron concentration in the upper atmosphere

by G. L. Austin

In an attempt to investigate the nature and motion of irregularities in the upper atmosphere, particularly the lower ionosphere or D region (60 to 100 km), a range of experimental methods are assessed. Emphasis is placed on phase measuring systems since they have been used relatively infrequently in ionospheric measurements. The differential absorption experiment for electron concentration is compared with a direct measuring differential phase method, with reasonable agreement. Both methods are investigated for sensitivity to the nature of the irregularities, with the result that there is found to be remarkably little dependence. Direction finding studies on D region irregularities are found to be difficult so that no comparison between the spaced receiver results for D region drifts is presented. Several amplitude and phase experiments to investigate the nature of reflectors and to search for possible atmospheric wave motions are described, with a variety of results.