Modeling study of the ionospheric effects during a total solar eclipse

On October 24, 1995 a total solar eclipse occurred with its path cutting th rough the low latitude region of Asia. In this paper the ionospheric effect s of this solar eclipse are investigated using a 2-D ionospheric theoretica l model. The results are compared with experimental observations made by si x ionosondes along the 120 degrees E meridian. Only the depression of solar EW fluxes during the eclipse has been taken into account in the calculatio n under the solar eclipse condition. Simulation results show that: (1) Duri ng the period of the eclipse the optical eclipse effects are quite clear at the low altitude of the ionosphere, while the responses to the eclipse are later and smaller but longer lasting at the high altitude ionosphere; (2) The lower the magnetic latitude, the stronger is the response to the solar eclipse. In low latitude region the values of f(0)F(2) on the eclipse day a re lower comparing with those on the control conditions, while h(m)F(2) val ues are higher. (3) Near the magnetic equator there is a sharp transition i n h(m)F(2) after the maximum phase, and a solar F-1.5 layer appeared; (4) A fter the maximum phase the effects of the eclipse lasted longer near Hainan , and a secondary depression occurred over magnetic equator. The mechanisms that may be responsible for eclipse-caused effects are discussed in the pa per.