The response of the ionospheric total electron content to the solar eclipse on August 11, 1999 Original Research Article

The GPS observations from EUREF permanent GPS network were used to observe the response of TEC (Total Electron Content) to the total solar eclipse under quiet geomagnetic conditions of the daytime ionosphere. The effect of the eclipse was detected in diurnal variations and more distinctly in the variations of TEC along individual satellite passes. The trough-like variations with a gradual decrease and followed by increase of TEC at the time of the eclipse were observed at all European stations. Depression of TEC amounted to 2–8 TECU. The delay of a minimum level of TEC with respect to the maximum phase of eclipse was 10–20 min. The effect of the eclipse was also detected at distance over 1500 km to the north from path of the eclipse. The high-resolution TEC maps produced with 15 minute intervals demonstrate the essential change in the structure of the ionosphere during the eclipse.