A Numerical Simulation And Analysis Of Hurricane Wilma's Concentric Eyewall

In this study, a high resolution explicit simulation of Hurricane Wilma is performed using the Weather Research and Forecasting (WRF) modeling system. The concentric eyewalls and its eyewall replacement process are simulated Successfully. on the base of model results, the effect of environmental vertical shear on hurricane's intensity and structure was analyzed first. Then a detailed investigate of the eye, inner eyewall, outer eyewall and moat region is performed. we show highlighting on the analysis on eyewall vortices, double eyewalls, characters of moat and the eyewall cycles and try to explain outeyewall's formation by the evolution of PV anomaly. Finally, we put a series of trajectories in different region of hurricane to have a look at the interaction between these different regions and to analyze the possible mechanism of formation of outer eyewall.The analysis shows: the vertical shear has notable effect on Wilma's struct -ure, both the vigorous convection and large radial out fow are located at the down shear and down shear left. there are several eyewall vortices in Wilma's eywall. these eyewall vortices will rotate around the center of hurricane anticlockwise and create local radial infow and outfow in the eyewall. The maximum vertical velocity and maximum heating just to the inside radially of the maximum winds may be the main reason of the eyewall's contracts. Moat region is characterized by intense rotation differential and weak upwell, whereas there is subsidence between 3～5km levels. Outer eyewall's formation may be related to the downward transport of middle PV. The down-ward curved of absolute angular momentum favor for the downward transport of middle PV anomaly, which will converge to hurricane center in the infow layer subsequently. The PV anomaly transporting inward will stack at a radius and intensify, then induce the WISHE mechanism to strengthen and ultimately create the outer eyewall. Thus the outer Eyewall's locations may determined by the position where the outward transport and inward transport PV make a encounter.Marked interactions, closely relatedin the vertical shear, exist between different regions of Wilma; As the outer eyewall is formed, it block the low level infow air to inner e,vewali and such blocking performance obvious selectivity of azimuthal position,which may also be related to the vertical shear.The air from lower level eyewall and inner evewall has positive role to outer evewall's evelopment,however the intrusion of mid- and high-level environmental air has negative role by its "ventilation".Intense "ventilation" mainly located at the upshear direction of vertical shear.Moat area particles mainly from lower level import and eyewatl supply;There is interaction between the inener and outer eyewall,which most obvious in the middle troposphere(～Tkm).Character of moat area particles is more closer to the one of outer eyewall because easer interaction between these two region.