DYANA CAMPAIGN RESULTS ON LONG-PERIOD ATMOSPHERIC WAVES OVER THUMBA AND BALASORE

The variation with altitude of the spectral amplitudes of the long period waves in the middle atmospheric zonal and meridonal wind over Thumba (8.5-degrees-N, 76.9-degrees-E) and Balasore (21.5-degrees-N, 86.9-degrees-E) have shown clearly the enhanced dissipation of the atmospheric waves in the lower stratosphere and near the stratopause. The amplitudes are, in general, large for the lower frequency (<0.1 cycles/day) waves in the troposphere. While propagating through the tropopause into the stratosphere and above, waves with periods in the range of 5-10 days suffer less attenuation. The dissipation of the atmospheric waves is found to be relatively large for frequencies below 0.1 cycles/day. The results are compared with earlier observational studies and theoretical computations on the propagation of equatioral waves through the middle atmosphere.