32nd Conference on Broadcast Meteorology/31st Conference on Radar Meteorology/Fifth Conference on Coastal Atmospheric and Oceanic Prediction and Processes

Monday, 11 August 2003
Doppler Profiler and Radar Observations of Tropical Storm Gabrielle During Landfall
Justin T. Walters, University of Alabama, Huntsville, AL; and K. R. Knupp
Tropical Storm Gabrielle made landfall at 1200 UTC 14 September 2001, along the west coast of Florida near Venice. At landfall, maximum sustained winds were close to hurricane strength of 30-33 m s-1. The Mobile Integrated Profiling System (MIPS) from the University of Alabama in Huntsville and a SMART-Radar from Texas A&M were deployed near the coast and made observations throughout the landfall period. The eye of the storm passed directly over the MIPS moving toward the northeast. As a consequence, two contrasting stratiform precipitation regions were sampled within the (a) offshore flow in advance of the circulation center, and (b) onshore flow to the west of the circulation center. Doppler spectra are analyzed to infer precipitation properties and processes over the layer between the surface and 10 km AGL. The initial stratiform precipitation region exhibited a thick bright band and a height that oscillated by several hundred meters. In contrast, the thinner bright band within trailing stratiform region varied little in height. Profiles of vertical particle velocity and spectral width also showed highly contrasting structures, particularly just above and within the bright band. Large spectral width values were observed above just above the bright in the initial stratiform region, but low spectral width existed within the bright band. Again, the trailing stratiform region showed much less variability in spectral width. A detailed analysis of Doppler spectra will be presented in the context of mesoscale vertical motion derived from single Doppler VAD analyses and dual Doppler analyses obtained from the SMART-R and Tampa Bay WSR-88D Doppler radars.

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