A Minimal Axisymmetric Tropical Cyclone Model

An axisymmetric version of the new three-dimensional tropical cyclone model of Zhu et al. will be described. The model is formulated in sigma-coordinates and has three vertical levels, one characterizing a shallow boundary layer and the other two representing the upper and lower troposphere, respectively. It has three options for treating cumulus convection on the sub-grid scale and a simple scheme for the explicit release of latent heat on the grid scale. The model is being used for basic studies of tropical cyclone behaviour, including an investigation of the factors that determine the size of a tropical cyclone and the differences in cyclone evolution when different convection schemes are implemented. Some of the recent findings will be reported in our talk.