Tuesday, 12 August 2003: 11:00 AM
The Hurricane Volume Velocity Processing Method
An extension of the Volume Velocity Processing (VVP) method has been developed to estimate the non-linear wind field associated with a hurricane. Radar-centered vertical profiles of the Cartesian wind components are partitioned into the contributions due to the penetrating environmental wind and those due to the winds intrinsic to the hurricane. The tangential and radial components of the intrinsic hurricane winds are resolved with respect to a cylindrical coordinate system centered on the hurricane’s vorticity center. In order to close the Hurricane VVP (HVVP) system of equations, a modified-Rankine vortex exponent is estimated from 1) the axisymmetric tangential momentum equation in those situations where HVVP calculates a radar-local radial inflow toward the vorticity center, and 2) an expression utilized in the Hurricane-customized Extension of the VAD (HEVAD) method in those situations where HVVP calculates a radar-local radial outflow away from the vorticity center. The HVVP and HEVAD methods are similar except the former provides a more accurate solution over the span of the independent variables by explicitly accounting for vertical variations in the wind components within the regression equations.
The HVVP method is tested on near-simultaneous volume scans of Hurricane Bret taken by the WSR-88D radars located at Brownsville (KBRO) and Corpus Christi (KCRP), Texas, near 2343 UTC 22 August 1999. The retrieved wind components are compared to a pseudo-triple-Doppler radar analysis of Bret that included Doppler velocity data from KBRO, KCRP and a NOAA P-3 aircraft. Preliminary results suggest that the HVVP method could provide reliable estimates of the penetrating environmental wind in the lower troposphere. Such estimates would be of great use to other wind analysis methods and numerical forecast models.
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