POTENTIAL VORTICITY IN HURRICANE GLORIA

Potential vorticity (PV)analyses for Hurricane Gloria of 1985 are deri ved from nested objective wind analyses of Omega dropwindsonde and air borne Doppler radar data. The analyses resolve eyewall-scale features in the inner vortex core and embed analyses of these features within t he larger-scale environment. Since three-dimensional geopotential heig ht fields required for evaluation of PV are not available in the core, they are derived using the balance equation. In the process of derivi ng the heights, the degree of gradient balance is evaluated. The 500-m b tangential winds in the core, averaged azimuthally on the four cardi nal points, are close to gradient balance outside the radius of maximu m wind. The resulting depiction of PV is the first presented for a rea l hurricane. Due to data deficiencies immediately outside the Doppler region, as well as inside the eye, smoothing of the wind data using a filter with a minimum 25-km spatial scale is required to derive a bala nced geopotential height distribution consistent with a statically sta ble vortex, The large-scale PV distribution evidences asymmetries in t he middle and upper troposphere that appear to be associated with Glor ia's translation to the northwest. Eyewall-scale PV in the core and PV of the azimuthally averaged vortex are also presented.