TOMOGRAPHIC IMAGING OF THE IONOSPHERIC MIDLATITUDE TROUGH

The paper describes an experimental campaign carried out in the United Kingdom in December 1990 during which simultaneous observations were made, using transmissions from the Navy Navigational Satellite System (NNSS) satellites, at four stations covering a latitudinal range of so me 8-degrees. The resulting measurements of total electron content hav e been used in a reconstruction algorithm to image the electron densit y on a two-dimensional grid for each of the satellite passes monitored . Results are presented showing the development of the mid-latitude tr ough throughout one night. The potential usefulness of tomographic tec hniques in ionospheric sensing is discussed in the light of the result s obtained.