Satellite beacon observations during eclipses have provided much information on the behavior of the ionosphere. A combination of Faraday rotation and differential phase measurements as well as ionosonde data can provide information on the topside and bottomside ionospheric behavior during an eclipse as well as on the production rate. Recent attention has been directed toward a study of the dynamics of the F region during an eclipse and the relation between the amount of depletion in the total electron content and the percent obscuration of the sun. Of particular interest is the time delay from the maximum obscuration to the maximum depletion of the total electron content. Further modeling studies are required in order to reproduce the experimental results. Further observations are also required in order to establish whether TID's are generated following a total solar eclipse as predicted theoretically. In particular, it appears that a more sensitive technique such as differential Doppler rather than Faraday rotation is required. The total solar eclipse of June 11, 1983, with its long totality time of 4–5 min over Indonesia and Papua New Guinea will provide an ideal opportunity for further studies of these unanswered questions.

During 1984 total electron content (TEC) data were gathered from Melbourne, a mid-latitude station, and from Macquarie Island in the southern auroral zone, using the Faraday rotation of geostationary satellite signals. Large-scale fluctuations in the TEC due to auroral activity were observed from Macquarie Island, and some of these disturbances were seen to propagate towards Melbourne with speeds of 200 to 1,000 m/s. Large-scale rapid decreases in TEC were observed during the evening hours of about one third of autumn equinox days studied. These decreases occurred at a geomagnetic latitude of approximately 60øS and could be associated with the main ionospheric trough travelling through the ray path from the satellite to the receiving station.