No abstract

No abstract

The evolution of topside sounding through rocket and satellite experiments is reviewed. Topside sounding has proved valuable for revealing the structure of the high ionosphere and for investigating the resonance properties of a magnetoplasma. The limits of our present knowledge of these rapidly developing subjects are discussed. Topside sounding is predicted to have a long and useful role in exploration of the ionosphere of earth and other planets.

No abstract

A description is given of an automatic method of using the radio pulse technique at oblique incidence to investigate the structure of the ionosphere. Sweep frequency photographic records were taken for the path Ottawa–Saskatoon (2355 km.). The records obtained confirm the validity of the theory relating vertical incidence to oblique incidence propagation. Sweeps showing such phenomena as E layer cutoff, transmission of the Pedersen ray, multiple reflections, are shown. It is found that the F1 layer is the important propagating layer rather than the F2 layer under certain conditions. Hence conventional methods of predicting frequencies over long distances require modification in these circumstances.

Winds in the ionosphere have been studied by a method described by S. N. Mitra using the fading of radio echoes at spaced receivers. A mean daily wind variation of nearly semidiurnal period and about 40 meters per second amplitude has been observed at a nominal height of 110 km. (Region E). The wind variation is consistent with the explanation that it is due to tidal oscillations of the atmosphere. A wind variation consistent with that expected from lunar atmospheric tides has also been detected at this level.The winds in the F region appear to increase in velocity with an increase of magnetic activity. A similar effect is not observed in the E region except during severe ionospheric disturbances.

No abstract

No abstract