2A.4
**Dynamics and energetics of tropical cyclone rainbands
Charmaine N. Franklin, RMIT Univ., Melbourne, Vic., Australia
Studies of tropical cyclone rainbands have often speculated that the bands have a negative feedback on the intensity of the storm by providing a partial barrier to the low level inflow (e.g. Barnes et al. 1983, Powell 1990) and limiting convection through the mesoscale descent of low qe air (Samsury and Zipser 1995). Conversely the typical stratiform mesoscale up/down draft couplets either side of the freezing level observed in rainbands provides a heating profile that generates potential vorticity and may have a positive affect on the intensification of the tropical cyclone (May and Holland 1999). These studies are usually restricted by the lack of temporal data and can not investigate the variation of wind and temperature within the rainbands or within and above the boundary layer. With the use of a three-dimensional triply nested movable mesh hydrostatic primitive equation model with explicit cloud microphysics and warm rain processes, the simulations of rainbands in tropical cyclones of various intensities and environmental conditions are studied. Results to be presented include: the organisation and circulations within the rainbands and their realism compared with observational studies; the potential vorticity budget to examine whether the bands contribute a significant flux of PV into the core of the storm and their role in the intensification of tropical cyclones, and; the energy budgets to investigate the role of downdrafts stabilising the low level air and inhibiting convection and radial inflow.
Session 2A, Tropical Cyclone Intensity Change Theory II (Parallel with Sessions 2B and 2C)
Tuesday, 23 May 2000, 1:15 PM-2:44 PM
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