TOWARD IONOSPHERIC TOMOGRAPHY IN ANTARCTICA - FIRST STEPS AND COMPARISON WITH DYNASONDE OBSERVATIONS

Total electron content (TEC) measurements obtained at two Antarctic st ations over nine months beginning early in 1994 have been analysed as a first step to performing ionospheric tomography. Two receiving syste ms were deployed at the Faraday and Halley research stations operated by the British Antarctic Survey to monitor signals from a random selec tion of passes of satellites in the Navy Navigational Satellite System . The resultant measurements of total electron content have been inver ted and combined with ionosonde measurements of true height and foF2 t o yield two-dimensional contour maps of ionospheric electron density. In spite of the poor geometry of the observations, some 130 satellite passes were found to be suitable for reconstruction using the techniqu es developed for ionospheric tomography. The contour maps of plasma de nsity have been compared with independent observations of the vertical electron density profile measured by the dynasonde ionospheric sounde r located at Halley. An example is presented of a deep trough investig ated by the technique, illustrating the potential of the tomographic m ethod for study of an extended spatial region of the ionosphere over i nhospitable terrain.