Possible evidence of non linear tidal coupling in TEC data

Long series of low solar activity TEC data integrated every one minute was analyzed using the autocorrelation technique. At early morning hours, a well-defined periodicity of 8 minutes was often detected. A model of nonlinear interaction between diurnal and semidiurnal tides of the neutral atmosphere was used to investigate the generation of nonlinear turbulence effects that could cause the observed phenomenon. Energy transfer from the tidal system generates a strong oscillation of half the Brunt-Vaisala period (16 minutes at the peak height of the F region) at the same hours of the day. Correlograms of data generated by the model simulation reproduce well the correlations observed using the experimental TEC data. The physical meaning of the results is discussed.