Disturbances of the western European ionosphere during the total solar eclipse of 11 August 1999 measured by a wide ionosonde and radar network

The 11 August 1999 Solar eclipse totality path ran across western Europe at near-constant latitudes of about 49 degreesN. It occurred at mid-time of a sequence of three days with steady solar wind and quiet magnetospheric conditions. Its response was observed by a score of ionospheric facilities, which will provide high-resolution probing of the various disturbances. First results allow us to compare the time fluctuations at various distances from totality on the eclipse and adjacent days, inside a 5 degrees West to 5 degrees East longitude area. In this preliminary work the foF1 and foF2 time changes are presented in contour maps on a 50 km size grid. They show the expected longitude transit of eclipse perturbation. We venture brief comments on the eclipse-own signatures as separate from the various wave oscillations detected prior to eclipse time by 12.4 MHz panoramic azimuth scans of the Losquet radar near Lannion (Brittanny). (C) 2001 Elsevier Science Ltd. All rights reserved.