Simulations have been made of tropical cyclone Connie which developed during the Australian Monsoon Experiment (AMEX) Phase 2. The aims are to investigate factors which affected the cyclone’s movement. Experiments were made using a primitive equation model with parametrised physical processes, which has been developed at JMA (Japan Meteorological Agency). Reprocessed objective analyses from the European Centre for Medium Range Weather Forecasts (ECMWF), and the JMA’s typhoon implantation scheme were used to generate the initial conditions. Analysis of the vorticity equation using data from the 24-hour simulations shows that the horizontal advection of absolute vorticity and the divergence term were dominant effects on the motion. This suggests that the track was determined by (a) steering flow, (b) the beta effect and (c) lower layer convergence which was generated and intensified by parametrised condensational heating. With regard to the beta effect, we illustrate that the motion in the three-dimensional atmosphere had similar characteristics to the motion of a vortex in a nondivergent barotropic flow. That is, the track was sensitive to tropical cyclone size, but insensitive to its inner core structure. Further, the track differences simulated from initial data containing circulations of different size became larger with simulation time. We conclude that to a first approximation, tropical cyclone Connie moved in a similar way to a vortex in a nondivergent barotropic flow, but its movement was modified by condensational heating.
Kurihara et al. (Sat,) studied this question.