3D Analysis of GW Propagation in the Ionosphere

Unique observation and analysis of gravity wave (GW) propagation in the ionosphere was performed on the basis of multipoint and multifrequency continuous Doppler sounding in the Czech Republic. The sounding radio waves of various frequencies reflect at different heights. Thus, the propagation of GWs can be studied in three-dimensional space using the time (phase) delays between observation of corresponding signatures at different reflection points that are separated both horizontally and vertically. The individual reflection points correspond to different sounding paths (transmitter-receiver pairs) and are usually at heights between 150 and 260 km, depending on ionospheric conditions. It is shown that the wave vectors of the observed GWs were mostly directed obliquely downward, which means that the energy propagated obliquely upward. It was observed that energy of GWs decreased with height in the upper atmosphere. The observed average attenuation was around 0.14 dB/km.