Modulation of tropical tropopause by wave disturbances

The three component wind data from MST radar at Gadanki (13.5∘N, 79.2∘E) are used to study the modulation of the tropical tropopause by wave disturbances in the winter seasons of 2000 and 2002 and in the summer season of 2001. Wave disturbances with periodicities in the range 18 days (d)-3 d have been observed to modulate the tropopause altitude and temperature. The zonal and meridional wind components and temperature at fixed altitudes around the tropopause are analyzed to delineate the nature of the wave disturbances. It is found that in the summer season, wave disturbances with periodicities in the range 18-7 d modulating the tropopause are manifestations of equatorial Kelvin waves. However, in the winter seasons, there is no clear evidence of modulation by equatorial Kelvin or Rossby gravity waves.