A Simplified System of Equations for Simulation of Tropical Cyclones

Abstract

Abstract A simplified system of equations which can simulate the development and mature stages of tropical cyclones is presented. The model is similar to that presented by Ooyama, except that the assumption of incompressible fluid layers is relaxed. Instead, the governing equations for a compressible fluid in isentropic coordinates are discretized vertically by considering three fluid layers with constant potential temperature. This makes the inclusion of thermodynamic processes more straightforward. The governing equations in the adiabatic case are mathematically equivalent to the equations used by Ooyama, except with an extra term in the pressure gradient force. The model equations are solved using a spectral method where the basis functions are the normal modes of the linearized equations. Numerical simulations show that the model sensitivity to vertical stability, sea surface temperature and midlevel moisture are similar to results from more general models. The sensitivity to these factors can be expl...