Effects of vertical wind shear on the structures and intensity of Hurricane Bonnie (1998)

A 5-day cloud-resolving simulation of Hurricane Bonnie (1998) with the finest grid length of 4 km is used to examine the effects of vertical wind shear (VWS) on hurricane structures and intensity changes. The results show wavenumber 1 asymmetries in the vertical motion and rainfall fields when VWS increases. It is found that the upper level strong ventilation on the upshear side tends to destroy the warm core in the eye while the VWS-induced intrusion of lower equivalent potential temperature from higher levels into the boundary layer core region plays an important role in weakening the storm. In view of little variations of the mean sea level temperature during the integration period, VWS may be considered as one of the major factors in determining the intensity change of Bonnie. Thus, the results indicate that the thermodynamical impact of VWS could be as significant as its dynamical impact on Bonnie’s intensity and intensity changes. The results suggest that higher-level ventilation is more detrimental to hurricane intensity compared to lower-level ventilation.