Amplitudes of medium scale gravity waves (GWs) in the ionosphere

The amplitude of GWs increases with height due to the decrease in the density of the atmosphere, but at the same time the attenuation of the waves also increases with height due to the dissipation of energy through friction. In this study, the propagation of GWs in the ionosphere is observed remotely, using multi-point, multi-frequency continuous HF Doppler sounding system situated in the western Czechia. The configuration of the system allows to determine not only the amplitude, but also the speed and direction of GWs propagation at different heights. An ionosonde located not far away from the Doppler sounding system is used to assign the reflection heights to individual measurements. The amplitudes of medium-scale atmospheric gravity waves propagating in the ionosphere are measured and statistically processed to investigate the daily and annual variations, and their relation to the speed of the neutral winds and the measurement height. Results from periods of solar maximum and minimum are compared.