On anomalous wind amplitudes in the lower ionosphere

According to known experiments both the zonal and meridional components of the wind demonstrate a clear increase in amplitude, starting from heights of 80–85 km, and the maximum amplitudes, which are reached at altitudes of 100–110 km. With a further increase in altitude, a gradual decrease in amplitudes begins. The wind maximum amplitudes turn out to be much larger than predicted by the theory of tidal movements in the ionosphere or the empirical Horizontal Wind Model (HWM). We propose a simple two-dimensional model to indicate the cause of abnormal amplitudes of wind motion in the lower ionosphere. The model is based on the existence of a well-established Ekman wind profile at the heights of the mesosphere-thermosphere. •Experiments demonstrate clear maximum in amplitudes of both the zonal and meridional components of the wind at altitudes of 100–110 km with gradual decrease in amplitudes both above and below these altitudes.•The wind maximum amplitudes turn out to be much larger than predicted by the theory.•The negative turbulent helicity of the Ekman flow in the upper atmosphere leads to an increase in the amplitude of the wind.