279-280The rocketsonde meteorological data for the Thumba equatorial station are examined to study wave periods of planetary wave disturbances at stratopause. The temperature, density and the height data obtained every Wednesday; regularly over the period 1972-74 are used to identify the stratopause. Power spectral analysis of the stratopause height and density is carried out. Dominant peaks in spectral power are observed at periods of 20 and 40 days
