Ann. Geophys., 26, 593-598, 2008
www.ann-geophys.net/26/593/2008/
© European Geosciences Union 2008
Long-term trends in foF2: their estimating and origin
J. Laštovička1, X. Yue2,3,4, and W. Wan2
1Institute of Atmospheric Physics, Academy of Sciences of the Czech Republic, 14131 Prague, Czech Republic
2Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
3Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
4Graduate School, Chinese Academy of Sciences, Beijing 100049, China
Abstract. This paper deals with two problems, methods of foF2 trend
determination and origin of trends in foF2, both being controversial in
current literature. We found that various regression-based methods and
artificial neural network-based method of Yue et al. (2006) provided
comparable results within uncertainties caused mainly by various ways of
removing/suppressing the dominant solar cycle effect. The role of
geomagnetic activity in the observed trends in foF2 was probably substantial
and might be still even rather dominant in the last quarter of the 20th
century.
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