We investigate seasonal behaviour of acoustic gravity waves (AGWs) in the thermosphere. For this purpose, measurements of HF Doppler sounding stations operated by or in cooperation with our institute are used.
These measurements are compared with previously reported studies which employed different techniques of ionospheric observations. The propagation of AGWs is found to have strong seasonal dependence.
AGWs in summer generally tend to propagate poleward in summer and equatorward in winter.