Extended Abstract (400K)12D.6
A modeling study of the sensitivity of landfalling hurricanes to surface evaporation and surface roughness.
Sytske K. Kimball, University of South Alabama, Mobile, AL
To unravel the complex interaction of physical processes that occur during hurricane landfall, a series of simplified model simulations are performed. These simulation consist of an idealized hurricane vortex embedded in weak (5 m s-1) southerly flow. The storm makes landfall on a straight west-to-east oriented coastline. The land surface is kept flat at a height of 0 m above sea level, and land cover is homogeneous in space. This way, factors like topography, changes in land-use, and coastline shape are excluded, allowing just the surface evaporation and roughness factors to be addressed. Each simulation includes a different, but relaisitc, land-use category with different evaporation- and roughness- characteristics. The storm’s intensity and size characteristics are compared and the impacts of the different surface characteristics on the distribution and intensity of rainfall and on low-level windspeed, are assessed. These simulations are performed with the PSU/NCAR mesoscale model, MM5, using 3 km and 1 km horizontal resolutions and 35-40 vertical levels. This allows explicit simulation of convective scale processes. These features were not included in previous idealized modeling studies of landfalling hurricanes.
The results from this simplified study will be used to understand future, more complex modeling studies of landfalling hurricanes using varying land-use distributions over space, the inclusion of topography, and coastlines of different shapes.
Session 12D, Tropical cyclones at landfall I
Thursday, 6 May 2004, 8:00 AM-9:30 AM, Napoleon III Room
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