ON THE DISPERSIVE NATURE OF F2-REGION TIDs OVER WALTAIR

Studies on F2-region TIDs are carried out at Waltair (Geo.lat.17.7°N, long.83.3° E) using phase path technique. The data obtained during the period 1974-:75 have been analysed to study the propagational characteristics of TIDs. The observed range of disturbances contains both the acoustic wave mode as well as gravity wave mode relevant to F-region heights, the maximum response occurring at a period of about 33 min. The speed of the disturbance is found to be varying with period in both the cases, thereby indicating a dispersion in the observed velocities. The observed nature of dispersion in the propagation of these TIDs has been discussed on the basis of the dispersive nature of the atmospheric waves in the ionosphere.