THE KINEMATIC STRUCTURE OF HURRICANE GLORIA (1985) DETERMINED FROM NESTED ANALYSES OF DROPWINDSONDE AND DOPPLER RADAR DATA

A set of three-dimensional, filtered, multiply nested objective analys es has been completed for the wind field of Hurricane Gloria for 0000 UTC 25 September 1985. At this time Gloria was one of the most intense hurricanes ever observed in the Atlantic basin, with a minimum sea le vel pressure of 919 mb. The nested analyses, based on observations fro m airborne Doppler radar and Omega dropwindsondes, simultaneously desc ribe eyewall and synoptic-scale features, and are the most comprehensi ve analyses of a single hurricane constructed to date. The analyses ha ve been used to document the multiscale kinematic structure of Gloria and to investigate the relationship between the kinematic fields and t he motion of the vortex. The analyses indicate that the vortex was unu sually barotropic. The radius of maximum wind (RMW) was nearly vertica l below 500 mb, with a slight inward slope with height between 750 and 550 mb. The strongest azimuthal mean tangential winds were found well above the boundary layer, near 550 mb, where the RMW was smallest. We speculate that this unusual structure was associated with a concentri c eye cycle. A persistent asymmetry in the distribution of eyewall con vection was associated with the vertical shear of the environmental fl ow. The vortex moved approximately 2.5 m s-1 faster than the deep laye r mean flow averaged at 667-km radius from the center. Barotropic mode ls have predicted a relationship between the relative motion of the vo rtex and the gradients of absolute vorticity in the cyclone's environm ent; however, the predicted relationship was not found for Gloria. The vortex also did not move with the mean flow in the immediate vicinity of the center; the motion of the hurricane was most consistent with t he 300-850-mb layer mean flow well outside the eyewall, at a radius of 65 km. The analyses suggest that the environmental flow near the cent er had been distorted by eyewall convection, with the scale of the dis tortion determined by the local Rossby radius of deformation.