Frictional Filling of Hurricanes

Abstract

As a hurricane moves from ocean to land, the surface roughness and the wind stress increase, which in turn causes the surface wind to blow across the isobars at an increased angle. The resulting increase in mass convergence in the surface friction layer is examined in the light of the Rossby-Montgomery theory on the influence of friction on surface flow, and the results are compared with the analysis of fifty years of hurricanes that moved into the United States. Those hurricanes are also analyzed to study the rate of pressure gradient decrease in the maximum wind zone. The results of this study indicate that frictional effect alone cannot dissipate the dangerous winds of a mature hurricane within the first eight to ten hours after moving onshore, but that dissipation is controlled essentially by the energy budget.