Ionospheric effects of a solar eclipse in the Cape Varde Islands
Abstract
The installation of two ionosondes at SAL (Cape Verde, Islands) and at Ascension Island (conjugate point to SAL) as well as three polarimeters at SAL, DAKAR and BATHURST (Gambia) in addition to the permanent ionosonde in DAKAR made it possible to detect various ionospheric effects of the eclipse. The passage of the entire eclipse at supersonic speed seems to have produced a gravity wave front due to the cooling. The simultaneous foF2 and total electron content minima determine the initial time for the passage of a gravity-wave-like wake with a velocity around 250 ms/1 and whose fundamental period is 18 mn. The ionospheric electric field perturbation is due to the ionization loss in the E region dynamo in a cylindrical region of 500 km radius. As a result of the upper F region 10 : 45 to 11 : 00 UT without any ionization loss at these levels. A thermospheric contraction flux appearing 20 mn after the eclipse maximum as well as a forced thermal diffusion flux were also noted. The results were essential for interpreting the more complex variations observed at subtropical and equatorial stations.
- Publication:
-
In AGARD Spec. Topics in HF Propagation 4 p (SEE N80-19372 10-32
- Pub Date:
- November 1979
- Bibcode:
- 1979sthp.agarU....M
- Keywords:
-
- Atmospheric Effects;
- Ionospheric Disturbances;
- Islands;
- Solar Eclipses;
- Thermosphere;
- E Region;
- F 2 Region;
- Gravity Waves;
- Ionospheric Electron Density;
- Magnetic Fields;
- Nations;
- Communications and Radar