In most dynamical studies of synoptic-scale phenomena, only the component of the Coriolis force contributed by the horizontal motion is considered, and only in the horizontal momentum equation.  The other terms are neglected based on a scale analysis.  However, it is shown that such an analysis may not be valid in a tropical cyclone (TC) and that these terms should be included.  The two terms are (1) f_w, the Coriolis force in the x-momentum equation due to vertical motion and (2) w_f, the Coriolis force in the vertical equation of motion due to the zonal wind. In this research, effects of the first term (i.e. f_w) are investigated.

            To study the effects of this term on the structure and motion of a TC, analytic analysis, barotropic model and baroclinic model (MM5) are employed. The results suggest that after f_w is included, the conserved potential vorticity of barotropic motion should include another term and it will change the structure and motion of a TC even on f-plane. Experiments in the barotropic and baroclinic model indicate that inclusion this term produces asymmetric structure of divergence and vorticity with rainfall distributions that are 20 to 30% of the symmetric parts.  The term f_w also causes the vortex to displace towards the southwest.