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Ann. Geophys., 26, 107-116, 2008
www.ann-geophys.net/26/107/2008/
© European Geosciences Union 2008
The ionospheric responses to the 11 August 1999 solar eclipse: observations and modeling
H. Le1,2, L. Liu1, X. Yue1,2, and W. Wan1
1Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
2Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
Abstract. A total eclipse occurred on 11 August 1999 with its path of totality
passing over central Europe in the latitude range 40°–50° N. The
ionospheric responses to this eclipse were measured by a wide ionosonde
network. On the basis of the measurements of foE, foF1, and foF2 at sixteen
ionosonde stations in Europe, we statistically analyze the variations of
these parameters with a function of eclipse magnitude. To model the eclipse
effects more accurately, a revised eclipse factor, FR, is constructed to
describe the variations of solar radiation during the solar eclipse. Then we
simulate the effect of this eclipse on the ionosphere with a mid- and low-latitude
ionosphere theoretical model by using the revised eclipse factor
during this eclipse. Simulations are highly consistent with the observations
for the response in the E-region and F1-region. Both of them show that the
maximum response of the mid-latitude ionosphere to the eclipse is found in
the F1-region. Except the obvious ionospheric response at low altitudes
below 500 km, calculations show that there is also a small response at high
altitudes up to about 2000 km. In addition, calculations show that when the
eclipse takes place in the Northern Hemisphere, a small
ionospheric disturbance also appeared in the conjugate hemisphere.
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