A numerical simulation of the development of tropical cyclones

A numerical experiment for the study of the development of tropical cyclones is performed with a 10-level axisymmetric model. In this model, the wind in the boundary layer is computed directly from the primitive equation of motion, but gradient balance is assumed above the boundary layer. The contribution of deep cumulus clouds to the heating of the large scale environment is parameterized along the lines of Kuo (1965) and Sundqvist (1970). The effect of the upward transport of momentum by cumulus clouds is also included in a crude manner. The experiment shows that the present model is capable of describing many features observed in real tropical cyclones. Our result differs from Sundqvist (1970) in one major aspect, namely, no rapid decay occurs after the mature stage if the external conditions and parameters remain unchanged, which is in agreement with the result of Ooyama (1969). The development process and the structure of the simulated tropical cyclone are discussed in some detail.