11A.7
A Numerical Study of Hurricane Erin (2001)
PAPER WITHDRAWN
Liguang Wu, NASA/GSFC, Greenbelt, MD; and S. A. Braun, J. Halverson, and G. M. Heymsfield
The Pennsylvania State Univerisity-National Center for Atmospheric Research mesoscale model MM5 is used to simulate Hurricane Erin (2001) at high resolution (4-km spacing) from its early development as a tropical cyclone depression on 7 September 2001, through a period of rapid intensification into a strong hurricane (8-9 September), and finally into a stage during which it maintains its intensity on 10 Septemeber. These three stages of development, intensification, and maintenance in the simulation are in good agreement with the observed evolution of Erin. The simulation is used to investigate the role of vertical wind shear in the changes of the precipitation structure that took place between 9-10 September by examining the effects of both storm-relative flow changes and changes in the shear-induced tilt. Qualitative agreement is found between the divergence pattern and advection of vorticity by the relative flow with convergence (divergence) generally associated with asymmetric inflow (outflow) in the eyewall region. The shift in the outer precipitation is consistent with a shift in the low-level relative inflow from northeastern to the northwestern side of the storm. Examination of the shear-induced tilt of the vortex shows that the change in the tilt direction is greater than that of the shear direction. Consistent with theory for adiabatic vortices, the maximum low-lwvwl convergence and upper-level divergence occurs in the direction of tilt. Consequently, both mechanisms may play roles in the changes in the precipitation pattern.
Session 11A, Tropical cyclone impacts and vulnerability
Wednesday, 5 May 2004, 3:45 PM-5:30 PM, Le Jardin Room
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