An Analysis of Stratospheric Wave Disturbances over the Tropical Pacific

Abstract

Stratospheric wave disturbances over the tropical western Pacific during Dec. 1968-Apr. 1969 are analysed for about 10 day period. It is found that two types of disturbances which propagate in the opposite direction are dominant in this period range. One is the Kelvin wave which is prevailing below 40 mb. The other is the westward propagating disturbance observed above 40 mb, which exhibits both zonal and meridional wind fluctuations. It may be identified with the n=1 Rossby wave. The vertical structure of these two types of waves is compared with the calculation based upon the wave theory (Lindzen, 1971, 1972). It has been noted by earlier studies that there exists a difference between the vertical structure of waves above and below the westerly shear zone when Kelvin waves are dominant. The present study suggests that the difference would most probably be due to the mixture of Rossby waves with Kelvin waves.