DYNAMICAL AND CHEMICAL FEEDBACK IN A 2-DIMENSIONAL INTERACTIVE MODEL OF THE MIDDLE ATMOSPHERE

A two-dimensional radiative-dynamical-chemical model is used to study the effect of dynamic and chemical feedback on the middle-atmospheric response to perturbations. The role of these feedbacks is examined in controlled experiments by perturbing the external forcing fields (e.g., solar heating and wave driving). The effects of planetary and gravity wave feedbacks and chemical feedbacks are isolated by using certain fixed variables from the results of the control run. The model experiments suggest the importance of gravity wave feedback on various perturbations throughout the stratosphere and mesosphere, as a result of the large magnitude of gravity wave forcing, and the parameterized gravity waves forcing being extremely sensitive to changes in the mean zonal wind. Therefore a realistic description of gravity wave breaking process appears to be essential for an accurate portrayal of how the middle atmosphere responds to changes. Chemical feedback effects, particularly through ozone, are also shown to be quite effective in modifying the influence of perturbations on the middle atmosphere.