DYNAMICAL INTERACTION BETWEEN THE LOWER STRATOSPHERE AND THE TROPOSPHERE

Abstract

The vertical flux of geopotential and the conversion between eddy available potential and eddy kinetic energy due to non-stationary disturbances are studied by solving numerically the diagnostic as well as the prognostic equations of a linearized 20-level model. The vertical distribution of these quantities thus computed compares well with those obtained by other authors from observed data and also with the results of general circulation experiments. The efforts of various parameters on these quantities are investigated by taking various experimental initial conditions for time integration of the prognostic equations. The parameters dealt with are: the scale of disturbance waves, the vertical tilt of the waves, the vertical profile of the zonal flow, the static stability, the ?-effect, and viscosity. The results show that the vertical tilt of the ultra-long and the long waves is important for the time change of eddy kinetic energy near or above the tropopause, and that the tilt of the short wave is important in the lower troposphere. In all cases, the westward tilt with increasing altitude contributes to the increase in kinetic energy, and the eastward tilt contributes to the reverse. The vertical wind shear is influential in determining the vertical distribution of the quantitites. The ?-effect is important to the ultra-long wave in that the eddy kinetic energy is increased in the upper atmosphere because of its presence. Likewise, the eddy kinetic energy is suppressed in the lower troposphere. Viscosity affects mainly the short wave in the lower troposphere. The effect of the vertically integrated divergence on the westward displacement of the ultra-long wave is also discussed.