The role of vertical structure of meridional wind in the intensification of Atlantic Hurricanes

This study examines the role of vertical structure of large-scale meridional winds on intensification of Atlantic hurricanes in different large scale background conditions using Reanalysis data as well a numerical model. The large-scale conditions associated with 6 hurricanes and 4 tropical storms are documented. The hurricanes are embedded in a stronger zonal wind environment in comparison to those of tropical storms that do not develop into hurricanes. It is shown that the barotropic structure of vorticity ahead of the convection center is the main forcing responsible for the intensification and propagation of the system. Vorticity budget analysis reveals that strong and barotropic (weak and equivalent barotropic) structures of meridional wind along the convection center produce a barotropic (equivalent barotropic) structure of vertical advection of horizontal vorticity and generate strong (weak) vorticity and heating ahead of convection and ultimately strengthen (weaken) the system. The results are further verified by using numerical model simulations. In one simulation a strong hurricane is identified and its meridional wind is nudged towards that of a weak tropical storm and in another experiment meridional wind of a weak tropical storm is nudged towards that of a strong hurricane. In both cases the role of meridional wind on hurricane intensification is successfully demonstrated as the hurricane weakens into a tropical storm and the tropical storm intensifies into a hurricane through changes in the meridional wind.