26th Conference on Hurricanes and Tropical Meteorology

Friday, 7 May 2004: 10:15 AM
The Effects of the Full Coriolis Force on the Structure and Motion of a Tropical Cyclone Part I: Effects Due To Vertical Motion
Napoleon I Room (Deauville Beach Resort)
Xudong Liang, Shanghai Typhoon Institute, Shanghai, China; and J. C. L. Chan and Y. Duan
Poster PDF (187.8 kB)

            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) fw, the Coriolis force in the x-momentum equation due to vertical motion and (2) wf, the Coriolis force in the vertical equation of motion due to the zonal wind. In this research, effects of the first term (i.e. fw) 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 fw 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 fw also causes the vortex to displace towards the southwest.

              

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