Numerical Studies of the Landfalling Characteristics and Dynamics of Hurricanes

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Accurate forecasts of the track and intensity of hurricanes at landfall can save lives and reduce economic losses. Current forecast accuracy suffers from poor representation of numerical model initial conditions, coarse grid resolution, and inadequate model physics. In addition, understanding of the external and internal processes controlling the track and intensity of these storms is rather limited. The main objectives of this research are, through numerical simulations of recent landfalling hurricanes, to (a) demonstrate that the tracks, extreme winds and precipitation structures of these storms can be reasonably predicted if high grid resolution, realistic model initial conditions and physics are incorporated; and (b) study the underlying physical and dynamical processes prior to, during and after landfall. These objectives are complementary to the goals of the U.S. Weather Research Program Hurricane Landfall research thrust.To achieve the above objectives, 5-day cloud-resolving simulations of two typical landfalling hurricanes will be performed, with the incorporation of more realistic initial conditions and improved physics schemes. The simulation results will be analyzed to address the following questions: Given the state-of-art model, to what extent can the observed tracks, intensity and the rates of intensity change, and precipitation be realistically reproduced? What are the landfalling characteristics of hurricanes as they move from sea to land? What are the roles of large-scale flows, cloud microphysics, boundary-layer processes, and surface conditions in determining the landfalling characteristics of hurricanes? What is the relative significance of vortex-Rossby and gravity-inertial waves in the development of spiral rainbands and eyewall convection? Successful completion of this research will help support the training of a postdoctoral researcher and a graduate student. It will also provide a better understanding of the landfalling characteristics of hurricanes, including the inner-core structural changes and their underlying dynamical and physical processes. This research will contribute to the improved prediction of hurricanes at landfall and their associated extreme winds and flooding rainfall events that have devastating effects on the society and environment of the U.S. coastal regions.