A new approach to the derivation of dynamic information from ionosonde measurements

A new approach is developed to derive dynamic information near the peak of the ionospheric F-layer from ionosonde measurements. This approach avoids deducing equivalent winds from the displacement of the observed peak height from a no-wind equilibrium height, so it need not de- termine the no-wind equilibrium height which may limit the accuracy of the deduced winds, as did the traditional servo theory. This approach is preliminarily validated with com- parisons of deduced equivalent winds with the measurements from the Fabry-Perot interferometer, the Millstone Hill inco- herent scatter radar and with previous works. Examples of vertical components of equivalent winds (VEWs), over Wuhan (114.4 E, 30.6 N, 45.2 dip), China in December 2000 are derived from Wuhan DGS-256 Digisonde data. The deduced VEWs show large day-to-day variations during the winter, even in low magnetic activity conditions. The diurnal pattern of average VEWs is more complicated than that predicted by the empirical Horizontal Wind Model (HWM). Using an empirical electric field model based on the observations from Jicamarca radar and satel- lites, we investigate the contributions to VEWs from neutral winds and from electric fields at the F-layer peak. If the elec- tric field model is reasonable for Wuhan during this period, the neutral winds contribute mostly to the VEWs, and the contribution from the E ◊ B drifts is insignificant.

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