Differential Doppler measurements of the ionosphere during a solar eclipse

The effects of the solar eclipse of 26 February 1979 on the ionosphere were measured using differential Doppler techniques. Navy navigation satellite passes were monitored at 12 sites located across the North American continent. These data yield a measurement of the vertical columnar electron content along a north-south line. Different sites monitoring the same pass provide simultaneous observations of ionospheric variations along different longitude lines. Two satellite passes occurred during or just after the eclipse. These data show a shoulder just northward of the umbra region and a trough just behind the umbra containing large horizontal gradients. This sharp trough recovered quickly with a half-life of about 10 min. (author)