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Ann. Geophys., 24, 851-860, 2006
www.ann-geophys.net/24/851/2006/
© European Geosciences Union 2006
A study of the ionogram derived effective scale height around the ionospheric hmF2
L. Liu, W. Wan, and B. Ning
Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
Abstract. The diurnal, seasonal, and solar activity variations of
the ionogram derived scale height around the ionospheric F-layer peak (Hm)
are statistically analyzed at Wuhan (114.4° E, 30.6° N) and the yearly
variations of Hm are also investigated for Wuhan and 12 other stations where
Hm data are available. Hm, as a measure of the slope of the topside electron
number density profiles, is calculated from the bottomside electron density
profiles derived from vertical sounding ionograms using the UMLCAR
SAO-Explorer. Results indicate that the value of median Hm increases with
increasing solar flux. Hm is highest in summer and lowest in winter during
the daytime, while it exhibits a much smaller seasonal variation at night. A
common feature presented at these 13 stations is that Hm undergoes a yearly
annual variation with a maximum in summer during the daytime. The annual
variation becomes much weaker or disappears from late night to pre-sunrise. In
addition, a moderate positive correlation is found between Hm with hmF2 and
a strong correlation between the bottomside thickness parameter B0 and Hm.
The latter provides a new and convenient way for empirical modeling the
topside ionospheric shape only from the established B0 parameter set.
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