6C.1 Axisymmetric concentric eyewall evolution in Hurricane Rita (2005)

Tuesday, 29 April 2008: 10:15 AM
Palms H (Wyndham Orlando Resort)
Michael M. Bell, NPS, Monterey, CA; and W. C. Lee, R. A. Houze, B. Smull, and M. T. Montgomery

Multiple legs of high-resolution airborne Doppler radar data were collected during Hurricane Rita's concentric eyewall phase by the NCAR ELDORA and NOAA P3 tail radars as part of the Hurricane Rainband and Intensity Experiment (RAINEX). This dataset provides a unique opportunity to examine the eyewall life-cycle. Previous tropical cyclone studies have highlighted the importance of the first order, mean circulation in vortex evolution. Rita's axisymmetric structure is obtained by azimuthally averaging the observations in a cylindrical coordinate system, and multiple circumnavigations of the inner core are used to examine the evolution of the eyewall replacement process. Results will be presented from 21 September 2005, where the storm was near maximum intensity preceding the concentric eyewall phase, and from 22 September when the outer eyewall was well developed. The radar analyses are also combined with in situ flight level and dropwindsonde measurements to further explore the dynamic and thermodynamic evolution of the multiple eyewalls. This evolution, including development of the 'moat' region, intensification of a secondary vortex sheet and convective ring, and reduction of low-level inflow to the primary eyewall will be presented.
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